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Resource

https://github.com/jaywcjlove/golang-tutorial

GO-practice

  • ctrl-shift-p -> go -> update -> select all

build/run

go build -> 產生執行檔

go run <file.go>

基本語法/操作

package main
import "fmt"
func main()  {
	fmt.Println("Hello world")
}

go version go env go build 檔名 go run 檔名 也可以 ./檔名

  • int int8 int16 int32 int64
  • float32 float64
  • string
  • bool
  • rune
  • byte
  • complex64 complex128
  • pointer 的init value 是nil
	var x int
	x = 10
	fmt.Println(x)
	var isTrue bool = true
	fmt.Println(isTrue)
	var c rune = 'b'
	fmt.Println(c)
	var s string = "Test Test Test"
	fmt.Println(s)
	var f float64 = 3.1415
	fmt.Println(f)

    // 也可以跟js一樣
    fmt.Println('a',"字串",2,3.14)

    //another assign 簡短格式
    //須給init value
    //不能提供数据类型。
    //只能用在函数内部
     i:=1

     //匿名變數 _ 
     //不站內存

input

fmt.Scanln(&圈圈叉叉變數)  

// & 是address
var x int
fmt.Println(&x) // print address

if

if true {
    //判斷條件不用 括號 XD  其他跟java一樣
    
}

for

for int  {
    //判斷條件不用 括號 XD  其他跟java一樣
    
}

switch

//case中不需要{}來分隔

//有點突兀的功能 fallthrough 進去後會接著執行下一個case

ans := "a"
switch ans {
    case "a": 
        fmt.Println("ans is a")
        fallthrough
    case "b":
        fmt.Println("ans is b")
    case "c":
        fmt.Println("ans is c")
    default:
        fmt.Println("no answer")
}

// ans is a
// ans is b


myfriend := "Paul"
switch myFriend {
    case "Amy", "Emily",: 
        fmt.Println("Hi, beautiful gril")
    case "Tony", "Paul":
        fmt.Println("Hi bro")
}


//Hi bro


//BTW case內還可以在寫判斷式
switch {
    case myMoney > 500:
        fmt.Println("buy Ferrari")
    case myMoney > 250:
        fmt.Println("buy BMW")
    default
        fmt.Println("buy Toyota")
}

pointer

	var x int = 5
	fmt.Println(x) //5

	fmt.Println(&x) //0xc0000160c8

	var pointer *int = &x
	fmt.Println(pointer) // 0xc0000160c8

	fmt.Println(*pointer) //5

struct

example:

type Point struct{
    x int
    y int
}

// 實體化 (java 的constructer)
func main(){
    var p1 Point=Point{3,4};
    var p2 Point=Point{x:1,y:2}
}

array

var arr [4]int
var arr2 [4]int{0,1,2,3}

fmt.Println(len(arr)) // get array length

a := [2]int{1, 2}
b := [...]int{1, 2}
c := [2]int{1, 3}
fmt.Println(a == b, a == c, b == c) // "true false false"
d := [3]int{1, 2}
fmt.Println(a == d) // compiler error, length not equals


//get data
for k, v := range a {
    fmt.Println(k, v)
}

_ -> ?

有時 slice 和 range 不需要 index 所以 用 "_" 省略掉

for _, num := range nums {
		sum += num
	}

reference https://ithelp.ithome.com.tw/articles/10187411 未完待續