swifter taipei 聊聊 swift 遊樂場、變數常數、數字與運算

Swifter .Taipei

https://goo.gl/328pSU

https://goo.gl/328pSU

Chapter 1: Playground Basics Chapter 2: Variables and Constants Chapter 3: Numeric Types and Operations Chapter 4: Strings Chapter 5: Making Decisions Chapter 6: Repeating Steps Chapter 7: Functions Chapter 8: Optionals Chapter 9: Arrays Chapter 10: Dictionaries Chapter 11: Sets Chapter 12: Structures Chapter 13: Class Basics Chapter 14: Advanced Classes Chapter 15: Enumerations Chapter 16: Properties Chapter 17: Methods Chapter 18: Protocols Chapter 19: Protocol-oriented Programming Chapter 20: Error Handling Chapter 21: Advanced Error Handling Chapter 22: Generics Chapter 23: Functional Programming

Chapter 1: Playground Basics Chapter 2: Variables and Constants Chapter 3: Numeric Types and Operations

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CPU RAM

Registry

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CPUlet a = “Hello World” let myAge = 20 let yourAge = 30 let total = myAge+yourAge

compiler

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0 4 2 3

以 10 進位⽽⾔，我們知道這個數字多⼤。

1000 100 10 1

1000 × 0 + 100 × 4 + 10 × 2 + 1 × 3Decimal:

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1 1 0 1

擅⽤ 10 進位的我們，只好將數字改⽤ 2 進位表達

8 4 2 1

8 × 1 + 4 × 1 + 2 × 0 + 1 × 1Decimal:

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8 4 2 1

bit bit bit bitbit bit bit bit

163264128

每 8 個 bit，我們稱為 1 個 byte

所以 1 個 byte 可以記到 255 這個數字

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4,294,967,29511111111111111111111111111111111

寫這麼多 0 跟 1 是很繁瑣的，所以我們更常⽤ 16 進位表⽰

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c 0 d e

1162564096

Decimal: 4096 × 12 + 256 × 0 + 13 × 16 + 1 × 14 = 43974

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c 0 d e

1162564096

c

0

d

e

1 1 0 0

0 0 0 0

1 1 0 1

1 1 1 0

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Free

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let number:Int = 10

為這筆資料取⼀個名字

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let number:Int = 10

為這筆資料取⼀個名字

abc

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let number:Int = 10

這筆資料可以存入整數

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let number:Int = 10

在這筆資料存入整數 10

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let number:Int = 10

這筆資料未來不能再變動內容

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var number:Int = 10

這筆資料未來能再變動內容

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var number:Int = 10

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var number = 10

因為裡⾯存入 10，所以 Swift 知道這是 Int

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有時候，某些資料要放在⼀起才有意義。

let coordinates: (Double,Double) = (2.1,3.5)

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let coordinates: (Double,Double) = (2.1,3.5)

coordinates.0 —> 2.1coordinates.1 —> 3.5

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let coordinates: (x:Double,y:Double) = (2.1,3.5)

coordinates.x —> 2.1coordinates.y —> 3.5

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按住 Option 鍵後點擊變數或常數的名稱

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let = 2+6 let = 10-2 let = 2*4 let = 24/3 let = 25%6

是的，你可以⽤中⽂當作變數/常數名稱

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0 0 0 10 0 0 0

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0 0 0 10 0 0

let = 1 << 3

0 0 0

let = 32 >> 2

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let a = 0 a = a+1

let a = 0 a = a-1

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let a = 0 a += 1

let a = 0 a -=1

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let hourlyRate = 19.5 let hoursWorked = 10 let totalCost = hourlyRate * hoursWorked

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let hourlyRate = 19.5 let hoursWorked = 10 let totalCost = hourlyRate * Double(hoursWorked)

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let yes:BOOL = true let no = false

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let doesOneEqualTwo = (1==2)false

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let doesOneEqualTwo = (1==2)let doesOneNotEqualTwo = (1!=2)let doesOneGreaterThanTwo = (1>2)let doesOneLessThanTwo = (1<2)

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let andTrue = (1<2) && (4 >3)

（1 ⼩於 2）⽽且（4 ⼤於 3）

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let andFalse = (1<2) && (3>4)

（1 ⼩於 2）⽽且（3 ⼤於 4）

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let orTure = (1<2) || (3>4)

（1 ⼩於 2）或者（3 ⼤於 4）

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let orFalse = (1==2) || (3==4)

（1 等於 2）或者（3 等於 4）

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let andTrue = true && truelet andFalse = true && false

let orTrue = true || falselet orFalse = false || false

Swifter .Taipei

2016.06.29 (Wed)PM19:30

2016.07.27 (Wed)PM19:30

http://goo.gl/iRxr9M

Swifter .Taipeihttp://www.meetup.com/taipei-swifter/

swifter taipei 聊聊 swift 遊樂場、變數常數、數字與運算

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