iteration (loop) part ii

ITERATION ITERATION (LOOP) (LOOP) PART IIPART II

Thanachat Thanomkulabut

Outline

For statementsNested loopsBreak statementsContinue statements

2

Looping or Iteration in Looping or Iteration in C#C#

3

foreachforeach

whilewhile

forfor

do…whiledo…while

Kinds of Iteration statements

4

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ครั้��งที่��ที่��ครั้��งที่��ที่��ซ้ำ��ได�ซ้ำ��ได�

for statement5

for for ( [initializers]; [condition]; [runner] )) statement;statement;

For For MultipleMultiple Statements Statements

For For SingleSingle Statement Statement

for ( for ( [initializers]; [condition]; [runner] ) { statement-1;statement-1; statement-2;statement-2; .. .. statement-N;statement-N;}

for statementfor statement6

STARTSTARTSTARTSTART

ENDENDENDEND

conditionconditionconditioncondition

true

false

StatementStatementStatementStatement

runnerrunnerrunnerrunner

initializersinitializersinitializersinitializers

for ( for ( [initializers]; [condition]; [runner] )) statementstatement;;

for statement7

STARTSTARTSTARTSTART

ENDENDENDEND

i <= 4i <= 4i <= 4i <= 4true

false

WriteLine(i)WriteLine(i)

i++i++i++i++

i = 1i = 1i = 1i = 1

static void Main() {

int i;for(i = 1; i <= 4; i++)Console.WriteLine(i);

}

Example of for statementExample of for statement

i

1

TRUE

1Output

2

2

3 344

5

FALSE

For Loop vs While Loop8

static void Main() static void Main() {

int int i;i;

for(for(i=1i=1; ; i<=i<=44; ; i++i++)) Console.WriteLine(i Console.WriteLine(i));;}

int int i=1;i=1; while (while ( i<=i<=4 4 )){{ Console.WriteLine(iConsole.WriteLine(i));; i++i++;;}}

For statement example9

static void Main()

{

int k;

for (k = 0; k <= 4; k++)

Console.Write("A");

Console.Write(k);

}

A A A A AOutpOutp

utut 5

for statement example Write the program to show even

number 2,4,6,...,n

10

static void Main(){ int k,n; Console.Write(“Input n :”); n = int.Parse(Console.ReadLine()); for ( ; ; ) {

}}

k = 1 k <= n k++

if(k%2==0) Console.WriteLine(k);

IMPROVE

Write the program to show even number 2,4,6,...,n

11

static void Main(){ int k,n; Console.Write(“Input n :”); n = int.Parse(Console.ReadLine()); for ( ; ; ) {

}}

k = 2 k <= n k=k+2

Console.WriteLine(k);

x power n(คู�ณสะสม )12

int i,n,x, product; Console.Write( “Enter value of x : “ ); x = int.Parse( Console.ReadLine( ) ); Console.Write( “Enter value of n : “ ); n = int.Parse( Console.ReadLine( ) );

product = 1; i=0;product = 1; i=0; while (i < n)while (i < n) {{ product = product *x;product = product *x; i = i+1;i = i+1; } } Console.WriteLine(“{0} power {1}={2}”, x,n, product);

Product = 1Product = 1*xProduct= (1*x)*xProduct= (1*x*x)*x

Find n factorial13

int n,x,fact; Console.Write( “Enter value of n : “ ); n = int.Parse( Console.ReadLine( ) ); fact = n;fact = n; x = n-1;x = n-1; while (x >= 1)while (x >= 1) {{ fact = fact*x;fact = fact*x; x = x-1;x = x-1; } } Console.WriteLine(“{0}! = {1}”, n, fact);

Test I : Problem #1: Find

N

i

i1

2

14

static void Main() static void Main() {{ int N=0, SUM=0, i=0;int N=0, SUM=0, i=0; Console.Write(”Please input number: ”);Console.Write(”Please input number: ”); N = int.Parse(Console.ReadLine());N = int.Parse(Console.ReadLine());

for ( for ( ??? ??? ; ; ??? ??? ; ; ??? ??? ) )

SUM = SUM + SUM = SUM + ??? ??? ;; Console.WriteLine(”SUM = {0}”, SUM);Console.WriteLine(”SUM = {0}”, SUM);}}

i =1

5i2

= 1*1 + 2*2 + 3*3 + 4*4 + 5*5

Outline

For statements Nested loops Break statements Continue statements

15

Nested Loops : Example16

for (int outer = 1; outer <= 4; outer++)

{

Console.WriteLine("Outer = {1} & Inner={0}”, 1, outer);



}


for (int outer = 1; outer <= 4; outer++) {

for (int inner = 1; inner <=3; inner++) {

Console.WriteLine("Outer = {1} & Inner={0}”, inner,outer);

}

}

Nested for loops

Do not use the same runner variable in the outer loop and the inner loop


for (int outer = 1; outer <= 4; outer++) {

for (int inner = 1; inner <=3; inner++)

{ Console.WriteLine("Outer = {1} & Inner = {0}" , inner ,outer);

}}

Outer = 1 & Inner = 1












Output


int outer = 1;

while (outer <= 4) {

int inner = 1 ;

while (inner <= 3) {

Console.WriteLine("Outer = {1} & Inner = {0}" , inner ,outer);

inner = inner +1;

}

outer = outer +1;

}

Nested while loops


int outer = 1;int outer = 1;

do {do {

int inner = 1;int inner = 1;

do {do {

Console.WriteLine("Outer = Console.WriteLine("Outer = {1}{1} & Inner = & Inner = {0}{0}"" , , inner inner ,,outerouter););

inner = inner +1inner = inner +1

} while (inner < 6);} while (inner < 6);

outer = outer + 1;outer = outer + 1;

inner = 1inner = 1

}while (outer < 5);}while (outer < 5);

Nested do...while loops

Test II : Nested Loops : Example Write the program

to Show output

21

112123123412345

int i,j;for( ; ; ){ for( , , ) {

}

}

Break statement

The break statement terminates the clos est enclosing loop or switch statement in

which it appears

22

Break statement example23

int i,j;for(i=1;i<=10;i++){ Console.WriteLine(i); if(i==5) break;}Console.Write(“final i = {0}”,i);

i

1

1Output

2345final i = 5

2345

Continue Statement24

int i=0,sum=0;do{ i++; if(i%2==0) continue; sum = sum+i;}while(i<10);Console.WriteLine("final sum={0}""final sum={0}",sum);

i

0

sum

01 +1

23 +3

+5

+7

+9

final sum = 25

Output

Continue statement example

25

int i=0,sum=0;for(i=1;i<=10;i++ ){ if(i%2==0) continue; sum = sum+i;}Console.WriteLine("final sum={0}",sum);

When program control reaches a continue statement, it transfers to the third section within the for loop parentheses (i++). Once this is complete, control transfers to the boolean expression for evaluation in the next iteration.

ANY QUESTION?

iteration (loop) part ii

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