giao trinh c++. thay binh

8/6/2019 Giao Trinh c++. Thay Binh

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CHNG 1

CC KHI NIM C S

CA LP TRNH HNG I TNG

Chng 1 trnh by nhng vn sau:

Tho lun v cch tip cn hng i tng, nhng nhc im ca lp

trnh truyn thng v cc c im ca lp trnh hng i tng.

Cc khi nim csca phng php hng i tng:

i tng

Lp

Tru tng ha dliu v bao gi thng tin

Ktha

Tng ng bi

Lin ktng

Truyn thng bo

Cc bc cn thitthit kchng trnh theo hng i tng

Cc u im ca lp trnh hng i tng

Cc ngn nghng i tng

Mt sng dng ca lp trnh hng i tng

1.1. Gii thiu

1.1.1. Tip cn hng i tng

Trong th gii thc, chung quanh chng ta l nhng i tng, l cc

thc th c mi quan h vi nhau. V d cc phng trong mt cng ty kinh

doanh c xem nh nhng i tng. Ccphngy c th l: phng qun

l, phng bn hng, phng k ton, phng tip th,... Mi phng ngoi nhng

cn b m nhim nhng cng vic c th, cn c nhng d liu ring nh

thng tin v nhn vin, doanh s bn hng, hoc cc d liu khc c lin quan

n b phn . Vic phn chia cc phng chc nng trong cng ty s to iu

kin d dng cho vic qun l cc hot ng. Mi nhn vin trong phng siu

khin v x l d liu ca phng . V d phng k ton ph trch v lng

bng nhn vin trong cng ty. Nu bn ang b phn tip th v cn tm thng

tin chi tit v lng ca n v mnh th s gi yu cu v phng k ton. Vi

cch lm ny bn c m bo l ch c nhn vin ca b phn k ton c

quyn truy cp d liu v cung cp thng tin cho bn. iu ny cng cho thy


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rng, khng c ngi no thuc b phn khc c th truy cp v thay i d liu

ca b phn k ton. Khi nim nh th vi tng hu nh c thc m

rng i vi mi lnh vc trong i sng x hi v hn na - i vi vic t

chc chng trnh. Mi ng dng c thc nh ngha nh mt tp cc thcth - hoc cc i tng, sao cho qu trnh ti to nhng suy ngha ca chng ta

l gn st nht v th gii thc.

Trong phn tip theo chng ta s xem xt phng php lp trnh truyn

thng t thy rng v sao chng ta cn chuyn sang phng php lp trnh

hng i tng.

1.1.2. Nhng nhc im ca lp trnh hng th tc

Cch tip cn lp trnh truyn thng l lp trnh hng th tc (LTHTT).Theo cch tip cn ny th mt h thng phn mm c xem nh l dy cc

cng vic cn thc hin nhc d liu, tnh ton, x l, lp bo co v in n

kt qu v.v... Mi cng vic sc thc hin bi mt s hm nht nh.

Nh vy trng tm ca cch tip cn ny l cc hm chc nng. LTHTT s dng

k thut phn r hm chc nng theo cch tip cn trn xung (top-down) to

ra cu trc phn cp. Cc ngn ng lp trnh bc cao nh COBOL, FORTRAN,

PASCAL, C, v.v..., l nhng ngn ng lp trnh hng th tc. Nhng nhcim chnh ca LTHTT l:

Chng trnh kh kim sot v kh khn trong vic b sung, nng cp

chng trnh. Chng trnh c xy dng theo cch TCHTT thc cht l

danh sch cc cu lnh m theo my tnh cn thc hin. Danh sch cc

lnh c t chc thnh tng nhm theo n v cu trc ca ngn ng lp

trnh v c gi l hm/th tc. Trong chng trnh c nhiu hm/th tc,

thng th c nhiu thnh phn d liu quan trng sc khai bo tng th(global) cc hm/th tc c th truy nhp, c v lm thay i gi tr ca

bin tng th. iu ny s lm cho chng trnh rt kh kim sot, nht l

i vi cc chng trnh ln, phc tp th vn cng trnn kh khn hn.

Khi ta mun thay i, b sung cu trc d liu dng chung cho mt s

hm/th tc th phi thay i hu nh tt c cc hm/th tc lin quan n d

liu .

M hnh c xy dng theo cch tip cn hng th tc khng m tcy , trung thc h thng trong thc t.


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Phng php TCHTT t trng tm vo hm l hng ti hot ng s

khng thc s tng ng vi cc thc th trong h thng ca th gii thc.

1.1.3. Lp trnh hng i tng

Lp trnh hng i tng (Object Oriented Programming - LTHT) lphng php lp trnh ly i tng lm nn tng xy dng thut gii, xy

dng chng trnh. i tng c xy dng trn csgn cu trc d liu vi

cc phng thc (cc hm/th tc) s th hin c ng cch m chng ta suy

ngh, bao qut v th gii thc. LTHT cho php ta kt hp nhng tri thc bao

qut v cc qu trnh vi nhng khi nim tru tng c s dng trong my

tnh.

im cn bn ca phng php LTHT l thit k chng trnh xoayquanh d liu ca h thng. Ngha l cc thao tc x l ca h thng c gn

lin vi d liu v nh vy khi c s thay i ca cu trc d liu th chnh

hng n mt s t cc phng thc x l lin quan.

LTHT khng cho php d liu chuyn ng t do trong h thng. D liu

c gn cht vi tng phng thc thnh cc vng ring m cc phng thc

tc ng ln v n c bo v cm vic truy nhp ty tin t bn ngoi.

LTHT cho php phn tch bi ton thnh tp cc thc thc gi l cc itng v sau xy dng cc d liu cng vi cc phng thc xung quanh cc

i tng .

Tm li LTHT c nhng c tnh ch yu nhsau:

1. Tp trung vo d liu thay cho cc phng thc.

2. Chng trnh c chia thnh cc lp i tng.

3. Cc cu trc d liu c thit k sao cho c tc cc i tng.

4. Cc phng thc xc nh trn cc vng d liu ca i tng c gnvi nhau trn cu trc d liu .

5. D liu c bao bc, che du v khng cho php cc thnh phn bn

ngoi truy nhp t do.

6. Cc i tng trao i vi nhau thng qua cc phng thc.

7. D liu v cc phng thc mi c th d dng b sung vo i tng no

khi cn thit.

8. Chng trnh c thit k theo cch tip cn bottom-up (di -ln).


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1.2. Cc khi nim cbn ca lp trnh hng i tng

Nhng khi nim c bn trong LTHT bao gm: i tng; Lp; Tru

tng ha d liu, bao gi thng tin; K tha; Tng ng bi; Lin kt ng;

Truyn thng bo.1.2.1. i tng

Trong th gii thc, khi nim i tng c hiu nh l mt thc th, n

c th l ngi, vt hoc mt bng d liu cn x l trong chng trnh,... Trong

LTHT th i tng l bin th hin ca lp.

1.2.2. Lp

Lp l mt khi nim mi trong LTHT so vi k thut LTHTT. N l

mt bn mu m t cc thng tin cu trc d liu v cc thao tc hp l ca cc

phn t d liu. Khi mt phn t d liu c khai bo l phn t ca mt lp

th n c gi l i tng. Cc hm c nh ngha hp l trong mt lp

c gi l ccphng thc (method) v chng l cc hm duy nht c th x

l d liu ca cc i tng ca lp . Mi i tng c ring cho mnh mt

bn sao cc phn t d liu ca lp. Mi lp bao gm: danh sch cc thuc tnh

(attribute) v danh sch cc phng thc x l cc thuc tnh . Cng thc

phn nh bn cht ca k thut LTHT l:

i tng = D liu + Phng thc

Chng hn, chng ta xt lp HINH_CN bao gm cc thuc tnh: (x1,y1)

to gc trn bn tri, d,r l chiu di v chiu rng ca HCN. Cc phng

thc nhp s liu cho HCN, hm tnh din tch, chu vi v hm hin th. Lp

HINH_CN c thc m t nh sau:


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Hnh 2.2 M t lp HINH_CN

Ch : Trong LTHT th lp l khi nim tnh, c th nhn bit ngay t vn

bn chng trnh, ngc li i tng l khi nim ng, n c xc nh

trong b nhca my tnh, ni i tng chim mt vng b nhlc thc hin

chng trnh. i tng c to ra x l thng tin, thc hin nhim vc

thit k, sau b hy b khi i tng ht vai tr.1.2.3. Tru tng ha dliu v bao gi thng tin

Tru tng ha l cch biu din nhng c tnh chnh v b qua nhng

chi tit vn vt hoc nhng gii thch. Khi xy dng cc lp, ta phi s dng

khi nim tru tng ha. V d ta c thnh ngha mt lp m t cc i

tng trong khng gian hnh hc bao gm cc thuc tnh tru tng nh l kch

thc, hnh dng, mu sc v cc phng thc xc nh trn cc thuc tnh ny.

Vic ng gi d liu v cc phng thc vo mt n v cu trc lpc xem nh mt nguyn tc bao gi thng tin. D liu c t chc sao cho

th gii bn ngoi (cc i tng lp khc) khng truy nhp vo, m ch cho

php cc phng thc trong cng lp hoc trong nhng lp c quan h k tha

vi nhau mi c quyn truy nhp. Chnh cc phng thc ca lp sng vai

tr nh l giao din gia d liu ca i tng v phn cn li ca chng trnh.

Nguyn tc bao gi d liu ngn cm s truy nhp trc tip trong lp trnh

c gi l s che giu thng tin.

HINH_CN

Thuc tnh :x1,y1

d,r

Phng thc :

Nhp_sl

Din tch

Chu vi

Hin th


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1.2.4. K tha

Ktha l qu trnh m cc i tng ca lp ny c quyn s dng mt

s tnh cht ca cc i tng ca lp khc. S k tha cho php ta nh ngha

mt lp mi trn cscc lp tn ti. Lp mi ny, ngoi nhng thnh phnc k tha, s c thm nhng thuc tnh v cc hm mi. Nguyn l k tha

h trcho vic to ra cu trc phn cp cc lp.

1.2.5. Tng ng bi

Tng ng bi l kh nng ca mt khi nim (chng hn cc php ton)

c th s dng vi nhiu chc nng khc nhau. V d, php + c th biu din

cho php cng cc s nguyn (int), s thc (float), s phc (complex) hoc

xu k t (string) v.v... Hnh vi ca php ton tng ng bi ph thuc vo kiud liu m n s dng x l.

Tng ng bi ng vai quan trng trong vic to ra cc i tng c cu

trc bn trong khc nhau nhng cng dng chung mt giao din bn ngoi (nh

tn gi).

1.2.6. Lin kt ng

Lin ktng l dng lin kt cc th tc v hm khi chng trnh thc hin

li gi ti cc hm, th tc . Nh vy trong lin kt ng, ni dung ca on

chng trnh ng vi th tc, hm s khng c bit cho n khi thc hin li

gi ti th tc, hm .

1.2.7. Truyn thng bo

Cc i tng gi v nhn thng tin vi nhau ging nh con ngi trao i

vi nhau. Chnh nguyn l trao i thng tin bng cch truyn thng bo cho

php ta d dng xy dng c h thng m phng gn hn nhng h thngtrong th gii thc. Truyn thng bo cho mt i tng l yu cu i tng

thc hin mt vic g . Cch ng x ca i tng c m t bn trong lp

thng qua cc phng thc.

Trong chng trnh, thng bo gi n cho mt i tng chnh l yu cu

thc hin mt cng vic c th, ngha l s dng nhng hm tng ng x l

d liu c khai bo trong i tng . V vy, trong thng bo phi ch ra

c hm cn thc hin trong i tng nhn thng bo. Thng bo truyn i

cng phi xc nh tn i tng v thng tin truyn i. V d, lp

CONGNHAN c th hin l i tng c th c i din bi Hoten nhn


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c thng bo cn tnh lng thng qua hm TINHLUONG c xc nh

trong lp CONGNHAN. Thng bo sc x l nh sau:

Trong chng trnh hng i tng, mi i tng ch tn ti trong thi

gian nht nh. i tng c to ra khi n c khai bo v s b hy b khi

chng trnh ra khi min xc nh ca i tng . S trao i thng tin ch

c th thc hin trong thi gian i tng tn ti.

1.3. Cc bc cn thit thit k chng trnh theo hng i tngChng trnh theo hng i tng bao gm mt tp cc i tng v mi

quan h gia cc i tng vi nhau. V vy, lp trnh trong ngn ng hng

i tng bao gm cc bc sau:

1. Xc nh cc dng i tng (lp) ca bi ton.

2. Tm kim cc c tnh chung (d liu chung) trong cc dng i tng

ny, nhng g chng cng nhau chia x.

3. Xc nh lp csda trn cscc c tnh chung ca cc dng itng.

4. T lp cs, xy dng cc lp dn xut cha cc thnh phn, nhng c

tnh khng chung cn li ca cc dng i tng. Ngoi ra, ta cn a ra cc lp

c quan h vi cc lp csv lp dn xut.

1.4. Cc u im ca lp trnh hng i tng

Cch tip cn hng i tng gii quyt c nhiu vn tn ti trong

qu trnh pht trin phn mm v to ra c nhng sn phm phn mm ccht lng cao. Nhng u im chnh ca LTHT l:

1. Thng qua nguyn l k tha, c th loi bc nhng on chng

trnh lp li trong qu trnh m t cc lp v mrng kh nng s dng cc lp

c xy dng.

2. Chng trnh c xy dng t nhng n th (i tng) trao i vi

nhau nn vic thit k v lp trnh sc thc hin theo quy trnh nht nh

ch khng phi da vo kinh nghim v k thut nh trc. iu ny m bort ngn c thi gian xy dng h thng v tng nng sut lao ng.

i tng Thng bo Thng tin


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3. Nguyn l che giu thng tin gip ngi lp trnh to ra c nhng

chng trnh an ton khng b thay bi nhng on chng trnh khc.

4. C th xy dng c nh x cc i tng ca bi ton vo i tng

ca chng trnh.5. Cch tip cn thit kt trng tm vo i tng, gip chng ta xy

dng c m hnh chi tit v gn vi dng ci t hn.

6. Nhng h thng hng i tng d mrng, nng cp thnh nhng h

ln hn.

7. K thut truyn thng bo trong vic trao i thng tin gia cc i

tng gip cho vic m t giao din vi cc h thng bn ngoi trnn n gin

hn.

8. C th qun l c phc tp ca nhng sn phm phn mm.

Khng phi trong h thng hng i tng no cng c tt c cc tnh

cht nu trn. Kh nng c cc tnh cht cn ph thuc vo lnh vc ng

dng ca d n tin hc v vo phng php thc hin ca ngi pht trin phn

mm.

1.5. Cc ngn nghng i tng

Lp trnh hng i tng khng l c quyn ca mt ngn ng no cbit. Cng ging nh lp trnh c cu trc, nhng khi nim trong lp trnh

hng i tng c th ci t trong nhng ngn ng lp trnh nh C hoc

Pascal,... Tuy nhin, i vi nhng chng trnh ln th vn lp trnh s tr

nn phc tp. Nhng ngn ngc thit kc bit, h trcho vic m t, ci

t cc khi nim ca phng php hng i tng c gi chung l ngn

ngi tng. Da vo kh nng p ng cc khi nim v hng i tng, ta

c th chia ra lm hai loi:1. Ngn ng lp trnh da trn i tng

2. Ngn ng lp trnh hng i tng

Lp trnh da trn i tng l kiu lp trnh h trchnh cho vic bao gi,

che giu thng tin v nh danh cc i tng. Lp trnh da trn i tng c

nhng c tnh sau:

Bao gi d liu

Cch che giu v truy nhp d liuTng to lp v xa b cc i tng


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Php ton ti bi

Ngn ng h trcho kiu lp trnh trn c gi l ngn ng lp trnh da

trn i tng. Ngn ng trong lp ny khng h trcho vic thc hin k tha

v lin kt ng, chng hn Ada l ngn ng lp trnh da trn i tng.Lp trnh hng i tng l kiu lp trnh da trn i tng v b sung

thm nhiu cu trc ci t nhng quan h v k tha v lin kt ng. V

vy c tnh ca LTHT c th vit mt cch ngn gn nh sau:

Cc c tnh da trn i tng + k tha + lin kt ng.

Ngn ng h trcho nhng c tnh trn c gi l ngn ng LTHT, v

d nh C++, Smalltalk, Object Pascal v.v...

Vic chn mt ngn ng ci t phn mm ph thuc nhiu vo cc

c tnh v yu cu ca bi ton ng dng, vo kh nng s dng li ca nhng

chng trnh c v vo t chc ca nhm tham gia xy dng phn mm.

1.6. Mt sng dng ca LTHT

LTHT ang c ng dng pht trin phn mm trong nhiu lnh vc

khc nhau. Trong s, c ng dng quan trng v ni ting nht hin nay l h

iu hnh Windows ca hng Microsoft c pht trin da trn k thut

LTHT. Mt s nhng lnh vc ng dng chnh ca k thut LTHT bao gm:+ Nhng h thng lm vic theo thi gian thc.

+ Trong lnh vc m hnh ha hoc m phng cc qu trnh

+ Cc csd liu hng i tng.

+ Nhng h siu vn bn, multimedia

+ Lnh vc tr tu nhn to v cc h chuyn gia.

+ Lp trnh song song v mng n-ron.

+ Nhng h tng ha vn phng v trgip quyt nh....


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CHNG 2

CC M RNG CA NGN NG C++

Chng 2 trnh by nhng vn sau y:

Gii thiu chung vngn ngC++Mt smrng ca ngn ngC++ so vi ngn ngC

Cc c tnh ca C++ htrlp trnh hng i tng

Vo ra trong C++

Cp pht v gii phng b nh

Bin tham chiu, hng tham chiu

Truyn tham scho hm theo tham chiu

Hm tr vgi tr tham chiuHm vi tham sc gi tr mc nh

Cc hm ni tuyn (inline)

Hm ti bi

2.1. Gii thiu chung v C++

C++ l ngn ng lp trnh hng i tng v l s mrng ca ngn ng

C. V vy mi khi nim trong C u dng c trong C++. Phn ln cc

chng trnh C u c th chy c trong C++. Trong chng ny ch tptrung gii thiu nhng khi nim, c tnh mi ca C++ h tr cho lp trnh

hng i tng. Mt s kin thc c trong C++ nhng c trong ngn ng C

s khng c trnh by li y.

2.2. Mt s mrng ca C++ so vi C

2.2.1. t li ch thch

Ngoi kiu ch thch trong C bng /* ... */ , C++ a thm mt kiu ch

thch th hai, l ch thch bt u bng //. Kiu ch thch /*...*/c dng

cho cc khi ch thch ln gm nhiu dng, cn kiu //c dng cho cc ch

thch trn mt dng. Chng trnh dch s b qua tt c cc ch thch trong

chng trnh.

V d: /* y l

cu ch thch trn nhiu dng */

//y l ch thch trn mt dng


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2.2.2. Khai bo bin

Trong C tt c cc cu lnh khai bo bin, mng cc b phi t ti u

khi. V vy v tr khai bo v v tr s dng ca bin c thcch kh xa nhau,

iu ny gy kh khn trong vic kim sot chng trnh. C++ khc phcnhc im ny bng cch cho php cc lnh khai bo bin c tht bt k ch

no trong chng trnh trc khi cc bin c s dng. Phm vi hot ng ca

cc bin kiu ny l khi trong bin c khai bo.

V d 2.1 Chng trnh sau y nhp mt dy s thc ri sp xp theo th t

tng dn:

#include

#include #include

void main()

{

int n;

printf("\n So phan tu cua day N=");

scanf("%d",&n);

float *x=(float*)malloc((n+1)*sizeof(float));for (int i=0;i


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getch();

}

2.2.3. Php chuyn kiu bt buc

Ngoi php chuyn kiu bt buc c vit trong C theo c php:(kiu) biu thc

C++ cn s dng mt php chuyn kiu mi nh sau:

Kiu(biu thc)

Php chuyn kiu ny c dng nh mt hm s chuyn kiu ang c gi.

Cch chuyn kiu ny thng c s dng trong thc t.

V d 2.2 Chng trnh sau y tnh sau tng S =n

1...

3

1

2

11

Vi n l mt s nguyn dng nhp t bn phm.

#include

#include

void main()

{

int n;

printf("\n So phan tu cua day N=");

scanf("%d",&n);

float s=0.0;

for (int i=1;i


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#include

#include

void main()

{

float a[20][20],smax;

int m,n,i,j,imax,jmax;

clrscr();

puts(" Cho biet so hang va so cot cua ma tran: ");

scanf("%d%d",&m,&n);

for (i=0;i


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printf("\n Co gia tri=%6.1f", smax);

printf("\n\n Tai hang %d cot %d",imax,jmax);

getch();

}

2.3. Vo ra trong C++

xut d liu ra mn hnh v nhp d liu t bn phm, trong C++ vn c

th dng hm printf() v scanf(), ngoi ra trong C++ ta c th dng dng

xut/nhp chun nhp/xut d liu thng qua hai bin i tng ca dng

(stream object) l cout v cin.

2.3.1. Xut dliu

C php: cout >bin N;

Ton tcinc nh ngha trc nh mt i tng biu din cho thit b vo

chun ca C++ l bn phm, cinc s dng kt hp vi ton t trch >>

nhp d liu t bn phm cho cc bin 1, 2, ..., N.

Ch :

nhp mt chui khng qu n k t v lu vo mng mt chiu a (kiu

char) c th dng hm cin.get nh sau: cin.get(a,n);

Ton t nhp cin>> s li k t chuyn dng \n trong bm. K t ny

c th lm tri phng thc cin.get. khc phc tnh trng trn cn dng

phng thc cin.ignore(1) b qua mt k t chuyn dng.

s dng cc loi ton t v phng thc ni trn cn khai bo tp tin dn

hng iostream.h

2.3.3. nh dng khi in ra mn hnh

quy nh s thc c hin th ra mn hnh vi p ch s sau du chm

thp phn, ta s dng ng thi cc hm sau:

setiosflags(ios::showpoint); // Bt chiu showpoint(p)setprecision(p);


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Cc hm ny cn t trong ton t xut nh sau:

cout


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cout >ts[i].d1>>ts[i].d2>>ts[i].d3;

ts[i].td=ts[i].d1+ts[i].d2+ts[i].d3;

}

for (i=0;i


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cout


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2.4.1. Ton tnew cp pht b nh

Ton t new thay cho hm malloc() v calloc() ca C c c php nh sau:

new Tn kiu ;

hoc new (Tn kiu);Trong Tn kiu l kiu d liu ca bin con tr, n c th l: cc kiu d

liu chun nh int, float, double, char,... hoc cc kiu do ngi lp trnh nh

ngha nh mng, cu trc, lp,...

Ch : cp pht b nhcho mng mt chiu, dng c php nh sau:

Bin con tr = new kiu[n];

Trong n l s nguyn dng xc nh s phn t ca mng.

V d: float *p = new float; //cp pht b nhcho bin con tr p c kiu intint *a = new int[100]; //cp pht b nh lu tr mng mt chiu a

// gm 100 phn t

Khi s dng ton t new cp pht b nh, nu khng b nh cp

pht, new s tr li gi tr NULL cho con tr. on chng trnh sau minh ha

cch kim tra li cp pht b nh:

double *p;

int n;cout>n;

p = new double[n]

if (p == NULL)

{

cout


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gim ca tng im, in danh sch th sinh sau khi sp xp, gii phng b nh

cp pht.

#include

#include #include

#include

#include

struct TS

{

char ht[20];

long sobd;

float td;

};

void main(void)

{

TS *ts;

int n;

coutn;

ts = new TS[n+1];

if (ts == NULL)

{

cout


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cout>ts[i].td;

}

for (i=0;i


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cout


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s thao tc trn cc bn sao ny ch khng x l trc tip vi cc tham s thc

s. Cch ny rt tt nu khi thc hin hm trong chng trnh khng cn lm

thay i gi tr ca bin gc. Tuy nhin, nhiu khi ta li mun nhng tham s

thay i khi thc hin hm trong chng trnh. C++ cung cp thm cch truynd liu cho hm theo tham chiu bng cch dng i l tham chiu. Cch lm

ny c u dim l khng cn to ra cc bn sao ca cc tham s, do d tit kim

b nhv thi gian chy my. Mt khc, hm ny s thao tc trc tip trn vng

nhca cc tham s, do d dng thay i gi tr cc tham s khi cn.

V d 2.7 Chng trnh sau s nhp dy s thc, sp xp dy theo th t tng

dn v hin th ra mn hnh.

#include #include

#include

void nhapds(double *a,int n)

{

for(int i=0;i


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double x[100];

int i,n;

clrscr();

coutn;

nhapds(x,n);

sapxep(x,n);

cout


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coutts[i].d2>>ts[i].d3;

ts[i].td=ts[i].d1+ts[i].d2+ts[i].d3;

}

}

void hvts(TS &ts1,TS &ts2)

{

TS tg=ts1;

ts1=ts2;

ts2=tg;

}

void sapxep(TS *ts,int n)

{

for(int i=0;i


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ints(ts[i]);

else

break;

getch();

}

V d 2.9 Chng trnh sau s nhp mt mng thc kch thc 20x20, in mng

nhp v in cc phn t ln nht v nh nht trn mi hng ca mng.

#include

#include

#include

#include

void nhapmt(float a[20][20],int m,int n)

{

for(int i=0;i


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for(int i=1;ix[vtmax]) vtmax=i;

if(x[i]>n;

nhapmt(a,m,n);

inmt(a,m,n);

float *p=(float*) a;

int vtmax,vtmin;

for(int i=0;i


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}

Trong trng hp ny biu thc c tr li trong cu lnh return phi l

tn ca mt bin xc nh t bn ngoi hm, bi v khi mi c th s dng

c gi tr ca hm. Khi ta tr v mt tham chiu n mt bin cc b khai bobn trong hm, bin cc b ny s b mt i khi kt thc thc hin hm. Do vy

tham chiu ca hm s khng cn ngha na.

Khi gi tr tr v ca hm l tham chiu, ta c th gp cc cu lnh gn hi

khc thng, trong v tri l mt li gi hm ch khng phi l tn ca mt

bin. iu ny hon ton hp l, bi v bn thn hm c gi tr tr v l mt

tham chiu. Ni cch khc, v tri ca lnh gn c th l li gi n mt hm c

gi tr tr v l mt tham chiu.Xem cc v d sau:

V d 2.10

#include

#include

int z;

int &f()// ham tra ve mot bi danh cua bien toan bo z

{

return z;

}

void main()

{

f()=50;//z=50

cout


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clrscr();

int b =10, a= 7, c= 20;

cout


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{

//Cc cu lnh

}

Ch :i vi cc hm c tham s mc nh th li gi hm cn vit theo quynh: Cc tham s vng mt trong li gi hm tng ng vi cc tham s mc

nh cui cng (tnh t tri sang phi), v d vi hm:

void f(int a, float x, char *st=TRUNG TAM, int b=1, double y = 1.234);

th cc li gi hm ng:

f(3,3.4,TIN HOC,10,1.0);//y tham s

f(3,3.4,ABC); //Thiu 2 tham s cui

f(3,3.4); //Thiu 3 tham s cui

Cc li gi hm sai:

f(3);

f(3,3.4, ,10);

V d 2.12

#include

#include

void ht(char *dc="TRUNG TAM",int n=5);void ht(char *dc,int n)

{

for(int i=0;i


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mi on chong trnh thc hin nhim v ca hm c thay bng li gi hm.

Tuy nhin hm cng c nhc im l lm l chm tc thc hin chng

trnh v phi thc hin mt s thao tc c tnh th tc mi khi gi hm nh: cp

pht vng nhcho cc tham s v bin cc b, truyn d liu ca cc tham scho cc i, gii phng vng nhtrc khi thot khi hm.

C++ cho kh nng khc phc c nhc im ni trn bng cch dng

hm ni tuyn. bin mt hm thnh hm ni tuyn ta vit thm t kha

inline vo trc khai bo nguyn mu hm.

Ch : Trong mi trng hp, t kha inline phi xut hin trc cc li gi

hm th trnh bin dch mi bit cn x l hm theo kiu inline.

V d hm f() trong chng trnh sau s khng phi l hm ni tuyn v inline

vit sau li gi hm.

V d 2.13

#include

#include

void main()

{

int s ;s=f(5,6);

cout


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hm theo kiu ni tuyn. T kho inline ch l mt t kho gi cho chng

trnh dch ch khng phi l mt mnh lnh bt buc.

V d 2.14 Chong trnh sau s dng hm inline tnh chu vi v din tch hnh

ch nht.#include

#include

inline void dtcvhcn(int a,int b,int &dt,int &cv)

{

dt=a*b;

cv=2*(a+b);

}void main()

{

int a[20],b[20],cv[20],dt[20],n;

coutn;

for(int i=0;i


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#include

inline void dtcvhcn(int a,int b,int &dt,int &cv);

void main()

{

int a[20],b[20],cv[20],dt[20],n;

coutn;

for(int i=0;i


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}

int max(int *x,int n)

{

int s=x[0];

for(int i=1;i


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Ch : Nu hai hm trng tn v trng i th trnh bin dch khng th phn

bit c. Ngay c khi hai hm ny c cng kiu khc nhau th trnh bin dch

vn bo li. V d sau xy dng hai hm cng c tn l f v cng mt i

nguyn a, nhng kiu hm khc nhau. Hm th nht c kiu nguyn( tr v a*a),hm th hai c kiu void. Chng trnh sau s b thng bo li khi bin dch.

V d 2.17

#include

#include

int f(int a);

void f(int a);

int f(int a){

return a*a;

}

void f(int a)

{

cout


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BI TP

1. Vit chng trnh thc hin cc yu cu sau y:

- Nhp d liu cho cc sinh vin (dng cu trc danh sch lin kt n),

cc thng tin ca sinh vin bao gm: m sinh vin, h tn, lp, imtrung bnh.

- Chng trnh c s dng ton t new v delete.

- In ra danh sch sinh vin c sp xp v th theo im trung bnh.

2. Vit chng trnh sp xp mt mng thc hai chiu theo th t tng

dn, trong chng trnh c c s dng ton t new v delete.

3. Vit cc hm ti bi tnh din tch tam gic, din tch hnh ch nht,

din tch hnh trn.

4. Vit chng trnh nhn hai ma trn Amxn v Bnxp , mi ma trn c cp

pht ng v cc gi tr ca chng pht sinh ngu nhin.


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CHNG 3

LP

Chng ny trnh by nhng vn sau y:

nh ngh

a lp

To lp i tng

Truy nhp n cc thnh phn ca lp

Con tri tng

Con tr this

Hm bn

Dliu thnh phn tnh, hm thnh phn tnh

Hm to, hm hy

Hm to sao chp

Lp l khi nim trung tm ca lp trnh hng i tng, n l s m

rng ca cc khi nim cu trc (struct) ca C. Ngoi cc thnh phn d liu,

lp cn cha cc thnh phn hm, cn gi l phng thc (method) hoc hm

thnh vin (member function). Lp c th xem nh mt kiu d liu cc bin,

mng i tng. T mt lp nh ngha, c th to ra nhiu i tng khc

nhau, mi i tng c vng nhring.

Chng ny s trnh by cch nh ngha lp, cch xy dng phng thc,

gii thch v phm vi truy nhp, s dng cc thnh phn ca lp, cch khai bo

bin, mng cu trc, li gi ti cc phng thc .

3.1. nh ngha lp

C php: Lp c nh ngha theo mu :

class tn_lp{

private: [Khai bo cc thuc tnh]

[nh ngha cc hm thnh phn (phng thc)]

public : [Khai bo cc thuc tnh]

[nh ngha cc hm thnh phn (phng thc)]

} ;

Thuc tnh ca lp c gi l d liu thnh phn v hm c gi lphng thc hoc hm thnh vin. Thuc tnh v hm c gi chung l cc


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thnh phn ca lp. Cc thnh phn ca lp c t chc thnh hai vng: vng

s hu ring (private) v vng dng chung (public) quy nh phm vi s

dng ca cc thnh phn. Nu khng quy nh c th (khng dng cc t kha

private v public) th C++ hiu l private. Cc thnh phn private chc sdng bn trong lp (trong thn ca cc hm thnh phn). Cc thnh phn public

c php s dng c bn trong v bn ngoi lp. Cc hm khng phi l hm

thnh phn ca lp th khng c php s dng cc thnh phn ny.

Khai bo cc thu c tnh ca lp: c thc hin y nh vic khai bo bin.

Thuc tnh ca lp khng th c kiu chnh ca lp , nhng c th l kiu con

tr ca lp ny,

V d:

class A

{

A x; //Khng cho php, v x c kiu lp A

A *p ; // Cho php, v p l con tr kiu lp A

} ;

nh ngha cc hm thnh phn: Cc hm thnh phn c thc xy

dng bn ngoi hoc bn trong nh ngha lp. Thng thng, cc hm thnh

phn n gin, c t dng lnh sc vit bn trong nh ngha lp, cn cc

hm thnh phn di th vit bn ngoi nh ngha lp. Cc hm thnh phn vit

bn trong nh ngha lp c vit nh hm thng thng. Khi nh ngha hm

thnh phn bn ngoi lp, ta dng c php sau y:

Kiu_tr_v_ca_hm Tn_lp::Tn_hm(khai bo cc tham s)

{ [ni dung hm]

}

Ton t :: c gi l ton t phn gii min xc nh, c dng ch ra

lp m hm thuc vo.

Trong thn hm thnh phn, c th s dng cc thuc tnh ca lp, cc hm

thnh phn khc v cc hm t do trong chng trnh.

Ch :

Cc thnh phn d liu khai bo l private nhm bo m nguyn l che

du thng tin, bo v an ton d liu ca lp, khng cho php cc hm

bn ngoi xm nhp vo d liu ca lp .


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Cc hm thnh phn khai bo l public c thc gi ti t cc hm

thnh phn public khc trong chng trnh .

3.2. To lp i tng

Sau khi nh ngha lp, ta c th khai bo cc bin thuc kiu lp. Cc binny c gi l cc i tng. C php khai bo bin i tng nh sau:

Tn_lp Danh_sch_bin ;

i tng cng c th khai bo khi nh ngha lp theo c php sau:

class tn_lp

{

...

} ;

Mi i tng sau khi khai bo sc cp pht mt vng nhring

cha cc thuc tnh ca chng. Khng c vng nhring cha cc hm thnh

phn cho mi i tng. Cc hm thnh phn sc s dng chung cho tt c

cc i tng cng lp.

3.3. Truy nhp ti cc thnh phn ca lp

truy nhp n d liu thnh phn ca lp, ta dng c php:Tn_i_tng. Tn_thuc_tnh

Cn ch rng d liu thnh phn ring ch c thc truy nhp bi nhng

hm thnh phn ca cng mt lp, i tng ca lp cng khng th truy nhp.

s dng cc hm thnh phn ca lp, ta dng c php:

Tn_i_tng. Tn_hm (Cc_khai_bo_tham_s_thc_s)

V d 3.1

#include

#include

class DIEM

{

private :

int x,y ;

public :

void nhapsl( ){


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cout >x>>y ;

}

void hienthi( )

{ cout


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A ob;

ob.nhap();

ob.hienthi();

getch();

}

Ch : Cc hm t do c th c cc i l i tng nhng trong thn hm

khng th truy nhp n cc thuc tnh ca lp. V d gi s nh ngha lp :

class DIEM

{

private :

double x,y ; // toa do cua diem

public :

void nhapsl()

{

cout > x>>y ;

}

void in()

{

cout


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#include

class Box

{

private:

int dai;

int rong;

int cao;

public:

int get_thetich(int lth,int wdth = 2,int ht = 3);

};

int Box::get_thetich(int l, int w, int h)

{

dai = l;

rong = w;

cao = h;

cout


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10 2 3 60

10 7 3 210

5 5 5 125

V d 3.4 V d sau minh ha vic s dng hm inline trong lp:

#include

#include

#include

class phrase

{

private:char dongtu[10];

char danhtu[10];

char cumtu[25];

public:

phrase();

inline void set_danhtu(char* in_danhtu);

inline void set_dongtu(char* in_dongtu);inline char* get_phrase(void);

};

void phrase::phrase()

{

strcpy(danhtu,"");

strcpy(dongtu,"");

strcpy(cumtu,"");

}

inline void phrase::set_danhtu(char* in_danhtu)

{

strcpy(danhtu, in_danhtu);

}

inline void phrase::set_dongtu(char* in_dongtu)

{

strcpy(dongtu, in_dongtu);

}


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inline char* phrase::get_phrase(void)

{

strcpy(cumtu,dongtu);

strcat(cumtu," the ");

strcat(cumtu,danhtu);

return cumtu;

}

void main()

{

phrase text;

cout


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int number;

public:

void print_it(const int data_value);

};

void constants::print_it(const int data_value)

{

number = data_value;

cout


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3.4. Con tri tng

Con tri tng dng cha a ch ca bin i tng, c khai bo

nh sau :

Tn_lp * Tn_con_ tr ;V d : Dng lp DIEM, ta c th khai bo:

DIEM *p1, *p2, *p3 ; // Khai bo 3 con tr p1, p2, p3

DIEM d1, d2 ; //Khai bo hai i tng d1, d2

DIEM d [20] ; // Khai bo mng i tng

C th thc hin cu lnh :

p1 = &d2 ; //p1 cha a ch ca d2, p1 tr ti d2

p2 =d ; // p2 tr ti u mng dp3 =new DIEM //to mt i tng v cha a ch ca n vo p3

truy xut cc thnh phn ca lp t con tri tng, ta vit nh sau :

Tn_con_tr -> Tn_thuc_tnh

Tn_con_tr -> Tn_hm(cc tham s thc s)

Nu con tr cha u a ch ca mng, c th dng con tr nh tn mng.

V d 3.6

#include #include

class mhang

{ int maso;

float gia;

public: void getdata(int a, float b)

{maso= a; gia= b;}

void show(){ cout


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int x,i;

float y;

cout getdata(x,y);

p++;}

for (i = 0; i


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cin >>this->x>>this->y ;

}

Con trthis l i th nht ca hm thnh phn. Khi mt li gi hm thnh

phn c pht ra bi mt i tng th tham s truyn cho con trthis

chnh la ch ca i tng .

V d: Xt mt li gi ti hm nhapsl() :

DIEM d1 ;

d1.nhapsl();

Trong trng hp ny ca d1 th this =&d1. Do this -> x chnh l d1.x v

this-> y chnh l d1.y

Ch : Ngoi tham sc bit this khng xut hin mt cch tng minh, hm

thnh phn lp c th c cc tham1 khc c khai bo nh trong cc hm

thng thng.

V d 3.7

#include

#include

class time

{ int h,m;public :

void nhap(int h1, int m1)

{ h= h1; m = m1;}

void hienthi(void)

{ cout


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time ob1, ob2,ob3;

ob1.nhap(2,45);

ob2.nhap(5,40);

ob3.tong(ob1,ob2);

cout


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...

}

double f2 (...)

{ ...

}

Cch 2: Dng t kha friend xy dng hm trong nh ngha lp . Mu vit

nh sau :

class A

{

private :

// Khai bo cc thuc tnh

public :

...

// Khai bo cc hm bn ca lp A

void f1 (...)

{

...

}

double f2 (...)

{

...

}

} ;

Hm bn c nhng tnh cht sau:

- Hm bn khng phi l hm thnh phn ca lp.

- Vic truy nhp ti hm bn c thc hin nh hm thng thng.

- Trong thn hm bn ca mt lp c th truy nhp ti cc thuc tnh ca i

tng thuc lp ny. y l s khc nhau duy nht gia hm bn v hm thng

thng.

- Mt hm c th l bn ca nhiu lp. Lc n c quyn truy nhp ti tt c

cc thuc tnh ca cc i tng trong cc lp ny. lm cho hm f trthnhbn ca cc lp A, B v C ta s dng mu vit sau :


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class A ; //Khai bo trc lp A

class B ; // Khai bo trc lp B

class C ; // Khai bo trc lp C

//nh ngha lp Aclass A

{

// Khai bo f l bn ca A

friend void f(... )

} ;

//nh ngha lp B

class B

{

// Khai bo f l bn ca B

friend void f(...)

} ;

//nh ngha lp C

class C

{

// Khai bo f l bn ca C

friend void f(...)

} ;

// Xy dng hm f

void f(...)

{

...

} ;

V d 3.8

#include

#include

class sophuc

{float a,b;

public : sophuc() {}

sophuc(float x, float y)

{a=x; b=y;}


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friend sophuc tong(sophuc,sophuc);

friend void hienthi(sophuc);

};

sophuc tong(sophuc c1,sophuc c2)

{sophuc c3;

c3.a=c1.a + c2.a ;

c3.b=c1.b + c2.b ;

return (c3);

}

void hienthi(sophuc c)

{cout


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public:

void nhap(int a)

{ v2=a;}

void hienthi(void)

{ cout


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cout


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int A::ts; // Khi gn cho ts gi tr 0

int A::ts = 1234; // Khi gn cho ts gi tr 1234

Ch : Khi cha khai bo th thnh phn tnh cha tn ti. Hy xem chng

trnh sau:V d 3.10

#include

#include

class HDBH

{

private:

char *tenhang;

double tienban;

static int tshd;

static double tstienban;

public:

static void in()

{

cout


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class HDBH

{

private:

int shd;

char *tenhang;

double tienban;

static int tshd;


public:

static void in()

{

cout


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Tn lp :: Tn hm thnh phn tnh(cc tham s thc s)

- V hm thnh phn tnh l c lp vi cc i tng, nn khng th dng hm

thnh phn tnh x l d liu ca cc i tng trong li gi phng thc

tnh. Ni cch khc khng cho php truy nhp cc thuc tnh (tr thuc tnhtnh) trong thn hm thnh phn tnh. on chng trnh sau minh ha iu ny:

class HDBH

{

private:

int shd;

char *tenhang;

double tienban;

static int tshd;


public:

static void in()

{

cout


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}

static void show_n(void)

{

cout


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c th thc hin mt s cng vic khc nhm chun b cho i tng mi. Khi

xy dng hm to cn lu nhng c tnh sau ca hm to:

- Tn hm to trng vi tn ca lp.

- Hm to khng c kiu tr v.- Hm to phi c khai bo trong vng public.

- Hm to c thc xy dng bn trong hoc bn ngoi nh ngha lp.

- Hm to c th c tham s hoc khng c tham s.

- Trong mt lp c th c nhiu hm to (cng tn nhng khc cc tham

s).

V d 3.13

class DIEM{

private:

int x,y;

public:

DIEM() //Ham tao khong tham so

{

x = y = 0;}

DIEM(int x1, int y1) //Ham tao co tham so

{

x = x1;y=y1;

}

//Cac thanh phan khac

};

Ch 1: Nu lp khng c hm to, chng trnh dch s cung cp mt hm to

mc nh khng i, hm ny thc cht khng lm g c. Nh vy mt i tng

to ra chc cp pht b nh, cn cc thuc tnh ca n cha c xc nh.

V d 3.14

#include

#inlcule

class DIEM

{

CH


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private:

int x,y;

public:

void in()

{

cout


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#include

#include

#include

class DIEM

{

private:

int x,y;

public:

DIEM()

{

x = y = 0;

}

DIEM(int x1, int y1)

{

x = x1; y = y1;

}

friend void in(DIEM d)

{

cout


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in(*d); // Goi ham ban in()

DIEM(2,2).in();// Goi ham thanh phan in()

DIEM t[3]; // 3 lan goi ham tao khong doi

DIEM *q; // Goi ham tao khong doi

int n;

cout > n;

q = new DIEM [n+1]; //n+1 lan goi ham tao khong doi

for (int i=0;i


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{

cout


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{

cout


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65

void rectangle::set(int new_dai,int new_rong)

{

dai = new_dai;

rong = new_rong;

}

int rectangle::get_area()

{

return (dai * rong);

}

int rectangle::get_extra()

{

return extra_data++; }

void main()

{

rectangle small, medium, large;

small.set(5, 7);

large.set(15, 20);

cout


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Gia tri du lieu tinh la : 2

Gia tri du lieu tinh la : 3

3.9. Hm to sao chp

3.9.1. Hm to sao chp mc nh

Gi s nh ngha mt lp ABC no . Khi :

- Ta c th dng cu lnh khai bo hoc cp pht b nh to cc i

tng mi, v d:

ABC p1, p2;

ABC *p = new ABC;

- Ta cng c th dng lnh khai bo to mt i tng mi t mt i

tng tn ti, v d:ABC u;

ABC v(u); // To v theo u

Cu lnh ny c ngha nh sau:

- Nu trong lp ABC cha xy dng hm to sao chp, th cu lnh ny

s gi ti mt hm to sao chp mc nh ca C++. Hm ny s sao chp ni

dung tng bit ca u vo cc bit tng ng ca v. Nh vy cc vng nhca u v

v s c ni dung nh nhau.- Nu trong lp ABC c hm to sao chp th cu lnh:

PS v(u);

s to ra i tng mi v, sau gi ti hm to sao chp khi gn v theo u.

V d sau minh ha cch dng hm to sao chp mc nh:

Trong chng trnh a vo lp PS (phn s):

+ Cc thuc tnh gm: t (t s) v m (mu).

+ Trong lp m khng c phng thc no c m ch c hai hm bn lcc hm ton t nhp (>>) v xut (


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private: int t,m;

public:

friend ostream& operator


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public:

PS(const PS &p)

{

t= p.t;

m= p.m;

}

};

Hm to sao chp trong v d trn khng khc g hm to sao chp mc nh.

Ch :

- Nu lp khng c cc thuc tnh kiu con tr hoc tham chiu th dng

hm to sao chp mc nh l .

- Nu lp c cc thuc tnh con tr hoc tham chiu, th hm to sao chp

mc nh cha p ng c yu cu.

class DT

{

private:

int n; // Bac da thuc

double *a; // Tro toi vung nho chua cac he so da thuc a0, a1,

public:

DT()

{

n = 0; a = NULL;

}

DT(int n1)

{n = n1;

a = new double[n1+1];

}

friend ostream& operator> (istream& is,DT &d);

};


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By gichng ta hy theo di xem vic dng hm to mc nh trong on

chng trnh sau s dn n sai lm nh th no:

DT d;

cin >> d; /* Nhp i tng d gm: nhp mt s nguyn dng v gn cho d.n, cp

pht vng nhcho d.n, nhp cc h s ca a thc v cha vo vng nhc

cp pht

*/

DT u(d);

/* Dng hm to mc nh xy dng i tng u theo d. Kt qu: u.n =

d.n v u.a = d.a. Nh vy hai con tr u.a v d.a cng trn mt vng nh.

*/

Nhn xt: Mc ch ca ta l to ra mt i tng u ging nh d, nhng c lp

vi d. Ngha l khi d thay i th u khng bnh hng g. Th nhng mc tiu

ny khng t c, v u v d c chung mt vng nhcha h s ca a thc,

nn khi sa i cc h s ca a thc trong d th cc h s ca a thc trong u

cng thay i theo. Cn mt trng hp na cng dn n li l khi mt trong

hai i tng u v d b gii phng (thu hi vng nhcha a thc) th i tng

cn li cng s khng cn vng nhna.

V d sau s minh ha nhn xt trn: Khi d thay i th u cng thay i v

ngc li khi u thay i th d cng thay i theo.

V d 3.20

#include

#include

#include

class DT

{

private:

int n; // Bac da thuc

double *a; // Tro toi vung nho chua cac he

//so da thuc a0,a1,...

public:

DT()

{


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this->n=0; this->a=NULL;

}

DT(int n1)

{

this->n=n1;

this->a= new double[n1+1];

}


};

ostream& operator


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clrscr();

cout d;

DT u(d);

cout


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};

DT::DT(const DT &d)

{

this->n = d.n;

this->a = new double[d.n+1];

for (int i=0;ia[i] = d.a[i];

}

ostream& operator


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clrscr();

cout d;

DT u(d);

cout


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public:

~A()

{

n = 0;

delete a;

}

};

V d 3.22

#include

class Count{

private:

static int counter;

int obj_id;

public:

Count();

static void display_total();

void display();

~Count();

};

int Count::counter;

Count::Count()

{

counter++;

obj_id = counter;

}

Count::~Count(){

counter--;

cout


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}

void Count::display()

{

cout


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BI TP

1. Xy dng lp thi gian Time. D liu thnh phn bao gm gi, pht giy.

Cc hm thnh phn bao gm: hm to, hm truy cp d liu, hm

normalize() chun ha d liu nm trong khong quy nh ca gi(0 gi< 24) , pht (0 pht


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7. Xy dng lp hng i Queue cha phn t kiu int. Cc hm thnh phn

bao gm: hm to, hm hy v nhng ton t hng i thng thng: hm

insert() thm phn t vo hng i, hm remove() loi b phn

t, hm isEmpty() kim tra hng i c rng khng, hm isFull() kimtra hng i c y khng. S dng mt mng thc hin.

4. Xy dng lp a thc v cc phng thc cng, tr hai a thc.

8. Xy dng lp Sinhvien qun l h tn sinh vin, nm sinh, im thi 9 mn

hc ca cc sinh vin. Cho bit sinh vin no c lm kha lun tt nghip,

bao nhiu sinh vin thi tt nghip, bao nhiu sinh vin thi li, tn mn thi li>

Tiu chun xt nh sau:

- Sinh vin lm kha lun phi c im trung bnh t 7 tr ln, trong khng c mn no di 5.

- Sinh vin thi t nghip khi im trung bnh nh hn 7 v im cc mn

khng di 5.

- Sinh vin thi li mn di 5.

9. Xy dng lp vector lu tr cc vectgm cc s thc. Cc thnh phn

d liu bao gm:

- Kch thc vect.

- Mt mng ng cha cc thnh phn ca vect.

Cc hm thnh phn bao gm hm to, hm hy, hm tnh tch v hng hai

vect, tnh chun ca vect(theo chun bt k no ).

10. Xy dng lp Phanso vi d liu thnh phn l t v mu s. Cc hm

thnh phn bao gm:

- Cng hai phn s, kt qu phi dc ti gin

- Tr hai phn s, kt qu phi dc ti gin

- Nhn hai phn s, kt qu phi dc ti gin

- Chia hai phn s, kt qu phi dc ti gin


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CHNG 4

TON T TI BI

Chng 4 trnh by cc vn sau:

nh ngh

a ton t

ti b

iMt slu khi xy dng ton tti bi

Mt sv d minh ha

4.1. nh ngha ton tti bi

Cc ton t cng tn thc hin nhiu chc nng khc nhau c gi l ton

t ti bi. Dng nh ngha tng qut ca ton t ti bi nh sau:

Kiu_tr_v operator op(danh sch tham s)

{//thn ton t}Trong : Kiu_tr_v l kiu kt qu thc hin ca ton t.

op l tn ton t ti bi

operator op(danh sch tham s) gi l hm ton t ti bi, n c th

l hm thnh phn hoc l hm bn, nhng khng th l hm tnh. Danh sch

tham sc khai bo tng t khai bo bin nhng phi tun theo nhng quy

nh sau:

- Nu ton t ti bi l hm thnh phn th: khng c tham s cho ton t mtngi v mt tham s cho ton t hai ngi. Cng ging nh hm thnh phn

thng thng, hm thnh phn ton t c i u tin (khng tng minh) l

con tr this .

- Nu ton t ti bi l hm bn th: c mt tham s cho ton t mt ngi v hai

tham s cho ton t hai ngi.

Qu trnh xy dng ton tti bi c thc hin nhsau:

- nh ngha lp xc nh kiu d liu sc s dng trong cc ton tti bi

- Khai bo hm ton t ti bi trong vng public ca lp

- nh ngha ni dung cn thc hin

4.2. Mt s lu khi xy dng ton tti bi

1. Trong C++ ta c th a ra nhiu nh ngha mi cho hu ht cc ton t

trong C++, ngoi tr nhng ton t sau y:

- Ton t xc nh thnh phn ca lp (.)- Ton t phn gii min xc nh (::)


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- Ton t xc nh kch thc (sizeof)

- Ton tiu kin 3 ngi (?:)

2. Mc du ng ngha ca ton tc mrng nhng c php, cc quy tc vn

phm nh s ton hng, quyn u tin v th t kt hp thc hin ca cc tont vn khng c g thay i.

3. Khng th thay i ngha cbn ca cc ton t nh ngha trc, v d

khng thnh ngha li cc php ton +, - i vi cc s kiu int, float.

4. Cc ton t = , ( ) , [ ] , -> yu cu hm ton t phi l hm thnh phn ca

lp, khng th dng hm bn nh ngha ton t ti bi.

4.3. Mt s v d

V d 4.1 Ton t ti bi mt ngi, dng hm bn#include

#include

class Diem

{

private:

float x,y,z;

public:Diem() {}

Diem(float x1,float y1,float z1)

{ x = x1; y = y1; z=z1;}

friend Diem operator -(Diem d)

{

Diem d1;

d1.x = -d.x; d1.y = -d.y;d1.z=-d.z;

return d1;

}

void hienthi()

{ cout


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clrscr();

Diem p(2,3,-4),q;

q = -p;

p.hienthi();

q.hienthi();

getch();

}

V d 4.2 Ton t ti bi hai ngi, dng hm bn

#include

#include

class Diem

{

private:

float x,y,z;

public:

Diem() {}


{ x = x1; y = y1; z=z1;}

friend Diem operator +(Diem d1, Diem d2)

{

Diem tam;

tam.x = d1.x + d2.x;

tam.y = d1.y + d2.y;

tam.z = d1.z + d2.z;

return tam;

}void hienthi()

{ cout


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d3=d1+d2;

d1.hienthi();

d2.hienthi();

cout


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}

V d 4.4 Ton t ti bi hai ngi, dng hm thnh phn

#include

#include class Diem

{

private:

float x,y,z;

public:

Diem() {}


{ x = x1; y = y1; z=z1;}

Diem operator +(Diem d2)

{

x = x + d2.x;

y = y + d2.y;

z = z + d2.z;

return (*this);

}

void hienthi()

{ cout


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}

V d 4.5

#include

#include class Diem

{

private:

int x,y;

public:

Diem() {}

Diem(int x1,int y1)

{ x = x1; y = y1;}

void operator -()

{

x = -x; y = -y;

}

void hienthi()

{ cout


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sophuc(float x, float y)

{a=x; b=y;}

sophuc operator +(sophuc c2)

{ sophuc c3;

c3.a= a + c2.a ;

c3.b= b + c2.b ;

return (c3);

}


{ cout


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{

a= a + c2.a ;

b= b + c2.b ;

return (*this);

}


{ cout


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{ cout


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string string::operator =(string s2)

{

strcpy(s,s2.s) ;

return *this;

}

int string::operator 0 ;

}

int string::operator ==(string s2)

{

return strcmp(s,s2.s)==0 ;

}

void main()

{ clrscr();

string o1 ("Trung Tam "), o2 (" Tin hoc"), o3;

cout


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if (o2 == o3)

cout


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}

Diem Diem::operator ++(int)

{

Diem temp = *this;

++*this;

return temp;

}

Diem & Diem::operator --()

{

x--;

y--;

return (*this);

}

Diem Diem::operator --(int)

{

Diem temp = *this;

--*this;

return temp;

}

void main()

{

clrscr();

Diem d1(5,10),d2(20,25),d3(30,40),d4(50,60);

cout


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--d3;

cout


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{

private:

int giatri;

public:

SO(int x=0)

{

giatri = x;

}

SO (SO &tso)

{

giatri = tso.giatri;

}

friend istream& operator>>(istream&,SO&);



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}


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BI TP

1. nh ngha cc php ton ti bi =, ==, ++, --, +=, trn lp Time (bi

tp 1 chng 3).2. nh ngha cc php ton ti bi =, ==, ++, --, +=, trn lp Date (bi

tp 2 chng 3).

1. nh ngha cc php ton ti bi +, -, *, =, ==, != trn lp cc ma trn vung.

2. nh ngha cc php ton ti bi +, -, * trn lp a thc.

3. nh ngha cc php ton ti bi +, -, *, /, =, ==, +=, -=, *=, /= , , =,

!= , ++, -- trn lp Phanso (bi tp 10 chng 3).

4. Ma trn c xem l mt vectm mi thnh phn ca n l mt vect. Theo

ngha , hy nh ngha lp Matran da trn vect. Tm cch chng

trnh dch hiu c php truy nhp m[i][j], trong m l mt i tng

thuc lp Matran.


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CHNG 5

K THA

Chng 5 trnh by cc vn sau:

n k

th

a,

a k

th

aHm to v hm hy i vi sktha

Hm o, lp cso

5.1. Gii thiu

K tha l mt trong cc khi nim csca phng php lp trnh hng

i tng. Tnh k tha cho php nh ngha cc lp mi t cc lp c. Mt

lp c th l lp cscho nhiu lp dn xut khc nhau. Lp dn xut s k

tha mt s thnh phn (d liu v hm) ca lp c s, ng thi c thmnhng thnh phn mi. C hai loi k tha l: n k tha v a k tha, c th

minh ha qua cc hnh v sau y:

Hnh 5.1.n k tha, lp A l lp csca lp B

(a) (b) (c)

Hnh 5.2. a k tha

Hnh (a): Lp A l lp csca lp B, lp B l lp csca lp C

Hnh (b): Lp A l lp csca cc lp B, C, D

Hnh (c): Lp A, B, C l lp csca lp D

5.2. n k tha

B

A

B C D

A B C

D

B

C


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5.2.1. nh ngha lp dn xut tmt lp cs

Gi s nh ngha lp A. C php xy dng lp B dn xut t lp A

nh sau:

class B: mode A{

private:

// Khai bo cc thuc tnh ca lp B

public:

// nh ngha cc hm thnh phn ca lp B

};

Trong mode c th l private hoc public vi ngha nh sau:- K tha theo kiu public th tt c cc thnh phn public ca lp cscng l

thnh phn public ca lp dn xut.

- K tha theo kiu private th tt c cc thnh phn public ca lp css tr

thnh cc thnh phn private ca lp dn xut.

Ch : Trong c hai trng hp trn th thnh phn private ca lp csl

khng c k tha. Nh vy trong lp dn xut khng cho php truy nhp n

cc thnh phn private ca lp cs.5.2.2. Truy nhp cc thnh phn trong lp dn xut

Thnh phn ca lp dn xut bao gm: cc thnh phn khai bo trong lp

dn xut v cc thnh phn m lp dn xut tha k t cc lp cs. Quy tc s

dng cc thnh phn trong lp dn xut c thc hin theo theo mu nh sau:

Tn i tng.Tn_lp::Tn_thnh_phn

Khi chng trnh dch C++ d dng phn bit thnh phn thuc lp no.

V d 5.1 Gi s c cc lp A v B nh sau:class A

{

public: int n;

void nhap()

{

coutn;}


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};

class B: public A

{

public: int m;

void nhap()

{

coutm;

}

};

Xt khai bo: B ob;

Lc : ob.B::m l thuc tnh n khai bo trong B

ob.A::n l thuc tnh n tha k t lp A

ob.D::nhap() l hm nhap() nh ngha trong lp B

ob.A::nhap() l hm nhap() nh ngha trong lp A

Ch : s dng cc thnh phn ca lp dn xut, c th khng dng tn lp,

ch dng tn thnh phn. Khi chng trnh dch phi t phn on bit

thnh phn thuc lp no: trc tin xem thnh phn ang xt c trng tn

vi cc thnh phn no ca lp dn xut khng? Nu trng th thnh phn

ca lp dn xut. Nu khng trng th tip tc xt cc lp cstheo th t: cc

lp c quan h gn vi lp dn xut sc xt trc, cc lp quan h xa hn

xt sau. Ch trng hp thnh phn ang xt c mt ng thi trong 2 lp c

s c cng mt ng cp quan h vi lp dn xut. Trng hp ny chng

trnh dch khng th quyt nh c thnh phn ny tha k t lp no v s

a ra mt thng bo li.

5.2.3. nh ngha li cc hm thnh phn ca lp cstrong lp dn xut

Trong lp dn xut c thnh ngha li hm thnh phn ca lp cs.

Nh vy c hai phin bn khc nhau ca hm thnh phn trong lp dn xut.

Trong phm vi lp dn xut, hm nh ngha li che khut hm c nh

ngha. Vic s dng hm no cn tun theo quy nh trn.

Ch : Vic nh ngha li hm thnh phn khc vi nh ngha hm qu ti.

Hm nh ngha li v hm bnh ngha li ging nhau v tn, tham s v gitr tr v. Chng ch khc nhau v v tr: mt hm t trong lp dn xut v hm


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kia th trong lp cs. Trong khi , cc hm qu ti ch c cng tn, nhng

khc nhau v danh sch tham s v tt c chng thuc cng mt lp. nh ngha

li hm thnh phn chnh l cscho vic xy dng tnh a hnh ca cc hm.

C++ cho php t trng tn thuc tnh trong cc lp csv lp dn xut.Cc thnh phn cng tn ny c th cng kiu hay khc kiu. Lc ny bn trong

i tng ca lp dn xut c ti hai thnh phn khc nhau c cng tn, nhng

trong phm vi lp dn xut, tn chung nhm chnh thnh phn c khai

bo li trong lp dn xut. Khi mun chnh thnh phn trng tn trong lp c

sphi dng tn lp ton t:: t trc tn hm thnh phn.

V d 5.2 Xt cc lp A v B c xy dng nh sau:

class A

{

private:

int a, b, c;

public:

void nhap()

{ couta;

coutb;

coutc;

}

void hienthi()

{ cout


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Xt khai bo : B ob; Lc cc cu lnh sau y l li :

ob.nhap();

ob.d=10;

ob.a = ob.b = ob.c = 5;ob.hienthi();

bi v i tng ob khng th truy nhp vo cc thnh phn private ca lp A v

B.

V d 5.3 Chng trnh minh ha n k tha theo kiu public:

#include

#include

class A

{

int a; //Bien private, khong duoc ke thua

public:

int b; //Bien public, se duoc ke thua

void get_ab();

int get_a(void);

void show_a(void);

};

class B: public A

{

int c;

public:

void mul(void);

void display(void);

};

void A::get_ab(void)

{ a = 5; b = 10;}

int A::get_a()

{ return a;}

void A::show_a()

{ cout


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void B::display()

{

cout


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void nhap()

{

coutx;

couty;

}

void hienthi()

{

cout


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}

Chng trnh cho kt qu:

Nhap toa do tam va ban kinh hinh tron

x = 2y = 3

r = 10

Hinh tron co tam:

x = 2 y = 3

Co ban kinh = 10

5.2.4. Hm to i vi tnh k tha

Cc hm to ca lp csl khng c k tha. Mt i tng ca lpdn xut v thc cht c th xem l mt i tng ca lp cs, v vy vic gi

hm to lp dn xut to i tng ca lp dn xut s ko theo vic gi n

mt hm to ca lp cs. Th t thc hin ca cc hm to s l: hm to cho

lp cs, ri n hm to cho lp dn xut.

C++ thc hin iu ny bng cch: trong nh ngha ca hm to lp dn

xut, ta m t mt li gi ti hm to trong lp cs. C php truyn tham

s t lp dn xut n lp csnh sau:Tn_ lp_dn_xut(danh sch i):Tn_ lp_c_s(danh sch i)

{

//thn hm to ca lp dn xut

};

Trong phn ln cc trng hp, hm to ca lp dn xut v hm to ca

lp css khng dng tham s ging nhau. Trong trng hp cn truyn mt

hay nhiu tham s cho mi lp, ta phi truyn cho hm to ca lp dn xut tt

ccc tham s m c hai lp dn xut v cscn n. Sau , lp dn xut ch

truyn cho lp csnhng tham s no m lp cscn.

V d 5.5 Chng trnh sau minh ha cch truyn tham s cho hm to ca lp

cs:

#include

#include

class Diem

{

private:


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double x, y;

public:

Diem()

{

x=y=0.0;

}

Diem(double x1, double y1)

{

x=x1; y=y1;

}

void in()

{

cout


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void main()

{

Hinhtron h(2.5, 3.5, 8);

clrscr();

cout


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~DX()

{cout


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5.3. a k tha

5.3.1. nh ngha lp dn xut tnhiu lp cs

Gi s nh ngha cc lp A, B. C php xy dng lp C dn xut t

lp A v B nh sau:class C: mode A, mode B

{

private:

// Khai bo cc thuc tnh

public:

// Cc hm thnh phn

};trong mode c th l private, public hoc protected. ngha ca kiu dn

xut ny ging nh trng hp n k tha.

5.3.2. Mt s v d va k tha

V d 5.7 Chng trnh sau minh ha mt lp k tha t hai lp cs:

#include

#include

#include

class M

{ protected :

int m;

public :

void getm(int x) {m=x;}

};class N

{ protected :

int n;

public :

void getn(int y) {n=y;}

};

class P : public M,public N


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{

public :

void display(void)

{ cout


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void nhap()

{ cout


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108

};

void main()

{ int i,n; ketqua sv[100];

coutn;

clrscr();

for(i=0;i


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{ protected : float d1,d2;

public :

void nhap_diem()

{

coutd1>>d2;

}

void hienthi_diem()

{ cout


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{ int i,n; ketqua sv[100];

coutn;

clrscr();

for(i=0;i


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class house : public Building

{ int bedrooms; //tong so phong ngu

int bathrooms; //tong so phong tam

public :

house(int f, int r, int ft, int br, int bth)

{ floors=f; rooms=r; footage=ft;

bedrooms=br; bathrooms=bth;

}

void show()

{ cout


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cout


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113

};

class B : public A

{

public:

void xuat()

{

cout


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p = &a; q = &b; r = &c;

Ta xt cc li gi hm thnh phn t cc con tr p, q, r:

p->xuat(); q->xuat(); r->xuat();

C 3 cu lnh trn u gi ti hm thnh phn xuat() ca lp A, bi v cccon tr p, q, r u c kiu lp A. Sdnh vy l v mt li gi (xut pht t

mt i tng hay con tr) ti hm thnh phn lun lun lin kt vi mt hm

thnh phn c nh v s lin kt ny xc nh trong qu trnh bin dch

chng trnh. Ta bo y l slin kt tnh.

C th tm lc cch thc gi cc hm thnh phn nh sau:

1. Nu li gi xut pht t mt i tng ca lp no , th hm thnh

phn ca lp sc gi.

2. Nu li gi xut pht t mt con tr kiu lp, th hm thnh phn ca lp

sc gi bt k con tr cha a ch ca i tng no.

Vn t ra l: Ta mun ti thi im con trang trn i tng no

th li gi hm phi lin kt ng hm thnh phn ca lp m i tng

thuc vo ch khng ph thuc vo kiu lp ca con tr. C++ gii quyt vn

ny bng cch dng khi nim hm o.

5.4.2. nh ngha hm o

Hm o l hm thnh phn ca lp, n c khai bo trong lp csv

nh ngha li trong lp dn xut. nh ngha hm o th phn khai bo hm

phi bt u bng t kha virtual. Khi mt lp c cha hm o c k tha,

lp dn xut snh ngha li hm o cho chnh mnh. Cc hm o trin khai

t tng ch o ca tnh a hnh l mt giao din cho nhiu hm thnh

phn. Hm o bn trong lp csnh ngha hnh thc giao tip i vi hm

. Vic nh ngha li hm o lp dn xut l thi hnh cc tc v ca hm linquan n chnh lp dn xut . Ni cch khc, nh ngha li hm o chnh l

to ra phng thc c th. Trong phn nh ngha li hm o lp dn xut,

khng cn phi s dng li t kha virtual.

Khi xy dng hm o, cn tun theo nhng quy tc sau:

1. Hm o phi l hm thnh phn ca mt lp;

2. Nhng thnh phn tnh (static) khng th khai bo o;

3. S dng con tr truy nhp ti hm o;


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4. Hm o c nh ngha trong lp c s, ngay khi n khng c s

dng;

5. Mu ca cc phin bn ( lp csv lp dn xut) phi ging nhau.

Nu hai hm cng tn nhng c mu khc nhau th C++ s xem nh hmti bi;

6. Khng c to ra hm to o, nhng c th to ra hm hy o;

7. Con tr ca lp csc th cha a ch ca i tng thuc lp dn

xut, nhng ngc li th khng c;

8. Nu dng con tr ca lp cs trn i tng ca lp dn xut th

php ton tng gim con tr s khng tc dng i vi lp dn xut, ngha

l khng phi con tr s tr ti i tng trc hoc tip theo trong lp

dn xut. Php ton tng gim ch lin quan n lp cs.

V d:

class A

{

...

virtual void hienthi()

{

cout


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cout


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117

B b; // b l bin i tng kiu B

p = &a; // p v a cng lp A

p = &b; // p l con tr lp cs, b l i tng lp dn xut

Ch : Khng cho php gn a chi tng ca lp cscho con tr ca lpdn xut, chng hn vi khai bo B *q; A a; th cu lnh q = &a; l sai.

V d 5.11 Chng trnh sau y minh ha vic s dng hm o:

#include

#include

class A

{

public:virtual void hienthi()

{

cout


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A *p;

A a; B b; C c;

a.hienthi(); //goi ham cua lop A

p = &b; //p tro to doi tuong b cua lop B

p->hienthi(); //goi ham cua lop B

p=&c; //p tro to doi tuong c cua lop C

p->hienthi(); //goi ham cua lop C

getch();

}

Chng trnh ny cho kt qu nh sau:

Lop A

Lop B

Lop C

Ch :

Cng mt cu lnh p->hienthi(); c tng ng vi nhiu hm khc

nhau khc nhau khi hienthi() l hm o. y chnh l s tng ng bi.

Kh nng ny cho php x l nhiu i tng khc nhau theo cng mt

cch thc.Cng vi li gi: p->hienthi(); (hienthi() l hm o) th li gi ny khng

lin kt vi mt phng thc cnh, m ty thuc v ni dung con tr.

l s lin ktng v phng thc c lin kt (c gi) thay i

mi khi c s thay i ni dung con tr trong qu trnh chy chng trnh.

V d 5.12 Chng trnh sau to ra mt lp csc tn lnumlu tr mt s

nguyn, v mt hm o ca lp c tn l shownum(). Lpnumc hai lp dn

xut louthex voutoct. Trong hai lp ny snh ngha li hm o shownum() chng in ra s nguyn di dng s h 16 v s h 8.

#include

#include

class num

{

public :

int i;num(int x) { i=x; }


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virtual void shownum()

{ cout


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{...};

clacc D : public B, public C

{...};

Vic chnh A l o trong cc lp B v C ngha l A s ch xut hin mtln trong lp D. Khai bo ny khng nh hng n cc lp B v C.

Ch : T kha virtual c th t trc hoc sau t kha public, private,

protected.

V d 5.13

#include

#include

class A

{ float x,y;

public:

void set(float x1, float y1)

{

x = x1; y = y1;

}

float getx()

{ return x;

}

float gety()

{ return y;

}

};

class B : virtual public A

{ };

class C : virtual public A

{ };

class D : public B, public C

{ };

void main()

{ clrscr();

D d;cout


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d.B::set(2,3);

cout


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Vi s k tha nh hnh v 5.4., th t gi hm to s l A, B, C v cui

cng l D. Chng trnh sau minh ha iu ny:

V d 5.14

#include #include

class A

{ float x,y;

public:

A() {x = 0; y = 0;}

A(float x1, float y1)

{cout


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public:

C(float x1, float y1):A(x1,y1)

{

cout


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B::B(float,float)

C::C(float,float)

D::D(float,float)

D d (2,3)

d.C::getx() = 2

d.B::getx() = 2

d.C::gety() = 3

d.B::gety() = 3

d1 (10,20)

A::A(float,float)

B::B(float,float)

C::C(float,float)

D::D(float,float)

d.C::getx() = 2

d.B::getx() = 2

d.C::gety() = 3

d.B::gety() = 3


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BI TP

1. Xy dng lp c tn l Stack vi cc thao tc cn thit. T hy dn xut t

lp stack i mt s nguyn dng sang hm bt k.

2. Vit mt phn cp k tha cho cc lp hnh t gic, hnh thang, hnh bnhhnh, hnh ch nht, hnh vung.

3. To mt lp csc tn l airship lu thng tin v s lng hnh khch

ti a v trng lng hng ha ti a m my bay c th chc. T

hy to hai lp dn xut airplane v balloon, lp airplane lu thng tin v kiu

ng c(gm ng ccnh qut v ng cphn lc), lp balloon lu thng

tin v loi nhin liu s dng cho kh cu (gm hai loi l hydrogen v

helium). Hy vit chng trnh minh ha.

4. Mt nh xut bn nhn xut bn sch. Sch c hai loi: loi c hnh nh

trang ba v loi khng c hnh nh trang ba. Loi c hnh nh trang ba

th phi thu ha sv ba. Vit chng trnh thc hin cc yu cu :

- To mt lp csc tn l SACH lu thng tin v tn sch, tc gi, s

trang, gi bn v nh ngha hm thnh phn cho php nhp d liu cho cc

i tng ca lp SACH.

- To lp BIA k tha t lp SACH lu cc thng tin : M hnh nh, tin

v v nh ngha hm thnh phn cho php nhp d liu cho cc i tng

ca lp BIA.

- To lp HOASY lu cc thng tin h tn, a ch ca ha s v nh

ngha hm thnh phn cho php nhp d liu cho cc i tng ca lp

HOASY.

- To lp SACHVEBIA k tha t lp BIA v lp HOASY v nh ngha

hm thnh phn cho php nhp d liu cho cc i tng ca lp

SACHVEBIA. Vit hm main() cho php nhp vo hai danh sch : danh sch

cc sch c v ba v danh sch cc sch khng c v ba (c th dng mng

tnh hoc mng con tr).

5. Xy dng lp hnh vung c tn l HVUONG vi cc d liu thnh phn nh

sau: di cnh. Cc hm thnh phn nhp d liu, hin th d liu, tnh

din tch, chu vi hnh vung. T lp HVUONG, xy dng lp dn xut c tnl CHUNHAT, l lp k tha ca lp HVUONG v c b sung thm thuc


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tnh sau: di cnh th hai. Cc hm thnh phn nhp d liu, hin th d

liu tnh din tch v chu vi hnh ch nht. Vit chng trnh minh ha.

6. Xy dng lp csCANBO c d liu thnh phn l m cn b, m n v,

h tn, ngy sinh. Cc hm thnh phn bao gm: nhp d liu cn b, hin thd liu. Lp dn xut LUONG k tha lp CANBO v c thm cc thuc

tnh: ph cp, h s lng, bo him. Hm thnh phn tnh lng cn b

theo cng thc:

lng = h s lng *290000 + ph cp - bo him

Hy thit k chng trnh p ng cc yu cu:

- Nhp danh sch cn b

- In bng lng cc cn b theo tng n v.7. Nhn vin trong mt cquan c lnh lng theo cc dng khc nhau. Dng

ngi lao ng hng lng t ngn sch Nh nc gi l cn b, cng chc

(dng bin ch). Dng ngi lao ng lnh lng t ngn sch ca cquan

gi l ngi lm hp ng. Nh vy h thng c hai i tng: bin ch v

hp ng.

- Hai loi i tng ny c c tnh chung l vin chc lm vic cho cquan.

Ty c th to nn lp cs qun l mt vin chc (lp Nguoi) baogm m s, h tn, lng.

- Hai lp k tha t lp cstrn:

+ Lp Bienche gm cc thuc tnh: h s lng, tin ph cp chc v.

+ Lp Hopdong gm cc thuc tnh: tin cng lao ng, s ngy lm

vic trong thng, h s vt gi.

Hy thit k cc lp trn v vit chng trnh minh ha.

8. Vit chng trnh qun l sch bo, tp ch ca th vin trong trng i hc,hng thng gi v khoa h tn ca cc gio vin v sinh vin qu thi hn

mn sch.

9. Vit chng trnh tnh v in bng lng hng thng ca gio vin v ngi

lm hp ng trong mt trng i hc. Gi s vic tnh tan tin lng c

cn c vo cc yu t sau:

- i vi gio vin: s tit dy trong thng, tin dy mt tit.

- i vi ngi lm hp ng: tin cng ngy, s ngy lm vic


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10. Gi s cui nm hc cn trao phn thng cho cc sinh vin gii, cc gio

vin c tham gia nghin cu khoa hc. iu kin khen thng ca sinh vin

l c im trung bnh ln hn 8. iu kin khen thng ca gio vin l c t

nht mt bi bo nghin cu khoa hc. S cu trc phn cp lp nh sau:

Nguoi

H tn

Ngy sinh

Cc phng

thc

Sinhvien

Lp

im trung

bnh

Cc phng

thc

Yu cu:

- Xy dng cc lp theo s k tha trn, mi lp c cc hm thnh phn nhp, xut d liu, hm kim tra khen thng.

- Hy vit hm main() cho php nhp vo d liu ca khng qu 100 sinh vin

v khng qu 30 gio vin. In ra danh sch sinh vin v gio vin c khen

thng.

Giaovien

B mn

S bi bo

Cc phng

thc


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11. Gi s ta c s k tha ca cc lp nh sau:

HINHHOC

HAICHIEU

Yu cu:

- Thit k cc lp c th in ra cc thng tin ca cc hnh (trn, ch nht, lp

phng) bao gm: din tch, chu vi, th tch.

- Vit chng trnh minh ha.

12. Vit chng trnh qun l vic mn v tr sch mt th vin theo

phng php lp trnh hng i tng. Chng trnh cho php:- ng k bn c mi vi thng tin l m v tn bn c, sin thoi

- Nhp sch mi vi thng tin l m sch, tn sch, s lng, nh xut bn.

- Mn v tr sch.

- Thng k bn c.

- Thng k sch.

BACHIEU

TRON CHUNHAT LAPPHUONG


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CHNG 6

KHUN HNH

6.1. Khun hnh hm

6.1.1. Khi nim

Ta bit hm qu ti cho php dng mt tn duy nht cho nhiu hm

thc hin cc cng vic khc nhau. Khi nim khun hnh hm cng cho php

s dng cng mt tn duy nht thc hin cc cng vic khc nhau, tuy nhin

so vi nh ngha hm qu ti, n c phn mnh hn v cht ch hn. Mnh hn

v ch cn vit nh ngha khun hnh hm mt ln, ri sau chng trnh bin

dch lm cho n thch ng vi cc kiu d liu khc nhau. Cht ch hn bi v

da theo khun hnh hm, tt c cc hm th hin c sinh ra bi chng trnhdch s tng ng vi cng mt nh ngha v nh vy s c cng mt gii

thut.

6.1.2. To mt khun hnh hm

Gi thit rng chng ta cn vit mt hmmina ra gi tr nh nht trong

hai gi tr c cng kiu. Ta c th vit mt nh ngha nh th vi kiu int nh

sau:

int min (int a, int b)

{

if (a


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Nh vy ta phi vit rt nhiu nh ngha hm hon ton tng t nhau, ch

c kiu d liu l thay i. Chng trnh dch C++ cho php gii quyt n gin

vn trn bng cch nh ngha mt khun hnh hm duy nht theo c php:

template tn hm(khai bo tham s){

//nh ngha hm

}

trong l cc kiu d liu c khai bo vi t kho

class, cch nhau bi du phy. Kiu d liu l mt kiu bt k, k c kiu class.

V d 6.1 Xy dng khun hnh cho hm tm gi tr nh nht ca hai s:

template Kieuso min(Kieuso a, Kieuso

b)

{

if (a


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- Cc bin truyn cho danh sch tham s ca hm phi chnh xc vi kiu

khai bo.

- Mun p dng c vi kiu lp th trong lp phi nh ngha cc ton t

ti bi tng ng.6.1.4. Cc tham s kiu ca khun hnh hm

Khun hnh hm c th c mt hay nhiu tham s kiu, mi tham si lin

sau t kho class. Cc tham s ny c th bt k u trong nh ngha ca

khun hnh hm, ngha l :

- Trong dng tiu (dng u khai bo template).

- Trong cc khai bo bin cc b.

- Trong cc ch th thc hin.Trong mi trng hp, mi tham s kiu phi xut hin t nht mt ln

trong khai bo danh sch tham s hnh thc ca khun hnh hm. iu hon

ton logic, bi v nhcc tham s ny, chng trnh dch mi c th sn sinh ra

hm th hin cn thit.

khun hnh hm min trn, mi ch cho php tm min ca hai s cng

kiu, nu mun tm min hai s khc kiu th khun hnh hm trn cha p ng

c. V d sau s khc phc c iu ny.

V d 6.2

#include

template kieuso1

min(kieuso1 a,kieuso2 b)

{

return a


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class SO

{

private:

int giatri;

public:

SO(int x=0)

{

giatri = x;

}

SO (SO &tso)

{

giatri = tso.giatri;

}

SO (){}; //Giong nhu ham thiet lap ngam dinh

~SO()

{ }

int operator(istream&,SO&);



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return a;

else

return b;

}

void main(){

float a =2.5;

int b = 8;

cout


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Nu khng c hm thng thng no tng ng chnh xc vi li gi, khi

ta kim tra tt c cc khun hnh hm c trng tn vi li gi, khi ta kim

tra tt c cc khun hnh hm c trng tn vi li gi; nu ch c mt tng ng

chnh xc c tm thy, hm th hin tng ng c sn sinh v vn cgii quyt; cn nu c nhiu hn mt khun hnh hm iu s gy ra li bin

dch v qu trnh dng.

Cui cng, nu khng c khun hnh hm ph hp, ta kim tra mt ln na

tt c cc hm thng thng cng tn vi li gi. Trong trng hp ny chng

ta phi tm kim s tng ng da vo c cc chuyn kiu cho php trong

C/C++.

6.2. Khun hnh lp6.2.1. Khi nim

Bn cnh khi nim khun hnh hm, C++ cn cho php nh ngha khun

hnh lp. Cng ging nh khun hnh hm, y ta ch cn vit nh ngha cc

khun hnh lp mt ln ri sau c th p dng chng vi cc kiu d liu

khc nhau c cc lp th hin khc nhau.

6.2.2. To mt khun hnh lp

Trong chng trc ta nh ngha cho lp SO, gi tr cc s l kiu int.

Nu ta mun lm vic vi cc s kii float, double,... th ta phi nh ngha li

mt lp khc tng t, trong kiu d liu int cho d liu giatri sc thay

bng float,double,...

trnh s trng lp trong cc tnh hung nh trn, chng trnh dch C++

cho php nh ngha mt khun hnh lp v sau , p dng khun hnh lp ny

vi cc kiu d liu khc nhau thu c cc lp th hin nh mong mun. V

d :

template class SO

{

kieuso giatri;

public :

SO (kieuso x =0);

void Hienthi();


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...

};

Cng ging nh cc khun hnh hm, template

xc nh rng l mt khun hnh trong c mt tham s ku kieuso .C++ s dng t kho class ch ni rng kieusoi din cho mt kiu d

liu no .

Vic nh ngha cc hm thnh phn ca khun hnh lp, ngi ta phn bit

hai trng hp:

Khi hm thnh phn c nh ngha bn trong nh ngha lp th khng c

g thay i.

Khi hm thnh phn c nh ngha bn ngoi lp, khi cn phi nhcli cho chng trnh bit cc tham s kiu ca khun hnh lp, c ngha l phi

nhc li template chng hn, trc nh ngha hm. V

d hm Hienthi() c nh ngha ngoi lp:

template void SO::Hienthi()

{

cout


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#include

#include

template class SO

{

kieuso giatri;

public :

SO (kieuso x =0);

void Hienthi(){

cout


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T x;

U y;

.....

Z fct1 (int);

.....

};

Mt lp th hin c khai bo bng cch lit k ng sau tn khun hnh

lp cc tham s thc, l tn kiu d liu, vi s lng bng cc tham s trong

danh sch ca khun hnh lp (template)

6.2.5. Tm tt

Khun hnh lp/hm l phng tin m t ngha ca mt lp/hm tngqut, cn lp/hm th hin l mt bn sao ca khun hnh tng qut vi cc kiu

d liu c th.

Cc khun hnh lp/hm thng c tham s ho. Tuy nhin vn c th

s dng cc kiu d liu c th trong cc khun hnh lp/hm nu cn.


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BI TP

1. Vit khun hnh hm tm s ln nht ca hai s bt k

2. Vit khun hnh hm tr v gi tr trung bnh ca mt mng, cc tham

s hnh thc ca hm ny l tn mng, kch thc mng.

3. Ci t hng i templete.

4. Vit khun hnh hm sp xp kiu d liu bt k.

5. Xy dng khun hnh lp cho cc ta im trong mt phng, cc

thnh phn d liu ca lp l toadox, toadoy.

6. Xy dng khun hnh lp cho vector qun l cc vector c thnh phn

c kiu ty .


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Ph lc

CC DNG XUT NHP

C++ s dng khi nim dng (stream) v a ra cc lp dng t chc

vic nhp xut. Dng c th xem nh mt dy tun t cc byte. Thao tc nhp lc cc byte t dng (gi l dng nhpinput) vo b nh. Thao tc xut l a

cc byte t b nhra dng (gi l dng xut- output). Cc thao tc ny l c

lp thit b. thc hin vic nhp, xut ln mt thit b c th, chng ta ch cn

gn dng tin vi thit b ny.

1.1. Cc lp stream

C 4 lp stream quan trng l: lp csios, t lp ios dn xut n hai lp

istream v iostream. Hai lp istream v ostream li dn xut vi lp iostream.

S k tha gia cc lp nh sau;

Lp ios: nh ngha cc thuc tnh c s dng lm cc cnh dng

cho vic xut nhp v cc ckim tra li, cc phng thc ca lp ios

phc v vic nh dng d liu nhp xut, kim tra li.

Lp iostream: cung cp ton t nhp >> v nhiu phng thc nhp

khc, chng hn cc phng thc: get, getline, read,ignore, peek, seekg,

tellg, ...

Lp ostream: cung cp ton t xut


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1.2. Dng cin v ton tnhp >>

1.2.1 Dng cin

cin l i tng ca lp istream. l dng nhp v c ni l b rng

buc ti hoc kt ni ti thit b nhp chun, thng thng l bn phm. Ccthao tc nhp trn dng cinng ngha vi nhp d liu t bn phm.

1.2.2. Ton ttrch >>

Ton t trch >> c s dng nh sau c d liu t dng cin:

cin>> bin;

nhp gi tr ca nhiu bin trn mt dng lnh ta dng c php sau:

cin>>bin 1>>bin 2>>...>>bin n;

1.3. Nhp k tv chui k t

C th dng cc phng thc sau (nh ngha trong lp istream) nhp k

t v chui: cin.get cin.getline cin.ignore

1.3.1. Phng thc get() c 3 dng:

Dng 1: int cin.get();

Dng c mt k t (k c khong trng).

Dng 2: istream& cin.get(char &ch);Dng c mt k t (k c khong trng) v t vo mt bin kiu char c

tham chiu bi ch.

Dng 3: istream& cin.get(char *str, int n, char d = \n);

Dng c mt dy k t (k c khong trng) v a vo vng nhdo str tr

ti. Qu trnh c kt thc khi xy ra mt trong hai tnh hung sau:

+ Gp k t gii hn (cho trong d). K t gii hn mc nh l \n.

+ nhn (n-1) k t.Ch :

+ K t kt thc chui \0 c b sung vo cui chui nhn c.

+ K t gii hn vn cn li trn dng nhp dnh cho cc lnh nhn tip

theo.

+ K t cn li trn dng nhp c th lm tri phng thc get() dng

3. V d: Xt on chng trnh:

char hoten[25], diachi[50], quequan[30];cout


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cin.get(ht,25);

cout


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143

char hoten[25], diachi[50];

cout


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int m=1234, n=56;

cout


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145

cout


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146

cout.setf(ios::left); //bat co ios::left

cout


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147

+ Khi ios::oct bt: s nguyn c in di dng cs 8

+ khi ios::hex bt: s nguyn c in di dng cs 16

Nhm 3 gm cc cnh dng s thc:

ios::fixed ios::scientific ios::showpointMc nh : c ios::fixed bt (on) v cios::showpoint tt (off).

+ Khi ios::fixed bt v c ios::showpoint tt th s thc in ra di dng thp

phn, s ch s phn phn (sau du chm) c tnh bng chnh xc n nhng

khi in th bi cc ch s 0 cui.

V d nu chnh xc n = 4 th

S thc -87.1500 c in: -87.15

S thc 23.45425 c in: 23.4543

S thc 678.0 c in: 678

+ Khi ios::fixed bt v cios::showpoint bt th s thc in ra di dng thp

phn, s ch s phn phn (sau du chm) c in ra ng bng chnh xc n.

V d nu chnh xc n = 4 th

S thc -87.1500 c in: -87.1500

S thc 23.45425 c in: 23.4543

S thc 678.0 c in: 6780000

+ Khi ios::scientific bt v cios::showpoint tt th s thc in ra di dng

khoa hc. S ch s phn phn (sau du chm) c tnh bng chnh xc n

nhng khi in th bi cc ch s 0 cui.

V d nu chnh xc n=4 th

S thc -87.1500 c in: -87.15e+01

S thc 23.45425 c in: 23.4543e+01

S thc 678.0 c in: 678e+02

+ Khi ios::scientific bt v cios::showpoint bt th s thc in ra di dng

m . S ch s phn phn (sau du chm) ca phn nh trc in ng bng

chnh xc n.

V d nu chnh xc n=4 th

S thc -87.1500 c in: -87.150e+01

S thc 23.45425 c in: 23.4543e+01

S thc 678.0 c in: 67800e+01

Nhm 4 gm cc hin th:

ios::uppercase ios::showpos ios::showbase


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Cios::showpos

+ Nu c ios::showpos tt (mc nh) th du cng khng c in trc s

dng.

+ Nu cios::showpos tt th du cng c in trc s dng.C ios::showbase bt th s nguyn h 8 c in bt u bng k t 0 v s

nguyn h 16 c bt u bng cc k t 0x. V d nu a = 40 th:

Dng in h 8 l: 050

Dng in h 16 l 0x28

Cios::showbase tt (mc nh) th khng in 0 trc s nguyn h 8 v khng

0x trc s nguyn h 16. V d nu a = 40 th:

Dng in h 8 l: 50

Dng in h 16 l 28

Cios::uppercase

+ Nu cios::uppercase bt th cc ch s h 16 (nh A, B, C,...) c in di

dng ch hoa.

+ Nu c ios::uppercase tt (mc nh) th cc ch s h 16 (nh A, B, C,...)

c in di dng ch thng.

1.4.5. Cc phng thc bt tt cCc phng thc ny nh ngha trong lp ios.

1. Phng thc long cout.setf(long f) ;

s bt cc clit k trong f v tr v mt gi tr long biu th cc cang bt.

2. Phng thc long cout.unsetf(long f) ;

s tt cc clit k trong f v tr v mt gi tr long biu th cc cang bt.

3. Phng thc long cout.flags(long f) ;

c tc dng ging nh cout.setf(long).4. Phng thc long cout.flags() ;

s tr v mt gi tr long biu th cc cang bt.

1.4.6. Cc b phn nh dng

Cc b phn nh dng (nh ngha trong tp tin iostream.h) bao gm:

dec // nh cios::dec

oct // nh cios::oct

hex // nh cios::hexendl // xut k t\n (chuyn dng)


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flush //y d liu ra thit b xut

V d Xt chng trnh sau:

#include

#include #include

void main()

{

clrscr();

cout.setf(ios::showbase);

cout


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cout


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{

clrscr();

float x=-87.1500, y=23.45425,z=678.0;

clog.setf(ios::scientific);

clog.precision(4);

clog.fill('*');

clog


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152

- fd(file disciptor) l ch s tp tin. Ch s tp tin nh sn i vi stdprn

(my in chun) l 4.

- Cc tham s buf v n

giao trinh c++. thay binh

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