Golang的陣列初始化方式及for-range遍歷

OldBoy~發表於2018-09-01
Golang陣列
package main
import (
    "fmt"
)


func main() {
    var arr1 [3]int = [3]int{1, 2, 3} //定義並初始化長度為3的陣列
    fmt.Println(arr1)  //[1 2 3]

    arr2 := [...] int {20:-1} //長度為20的陣列，只有最後一個是-1，其他都是0
    fmt.Println(arr2) //[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1]

    arr3 := [3]int{5, 6, 7}  //定義並初始化長度為3的陣列
    fmt.Println(arr3) //[5 6 7]

    arr4 := [...]int{1:100, 3:50, 0:200}  //指定下標的陣列，一共四個，因為最大是3
    fmt.Println(arr4) //[200 100 0 50]

    var arr5 [3]int   //3個int型的陣列，初始值是3個0,陣列“零值”狀態
    fmt.Println(arr5) //[0 0 0]

    //二維陣列
    arr6 := [3][4]int{{0,1,2,3},{6,7,9},{6,4,5}}
    //列印一維陣列長度
    fmt.Println(len(arr6))  //3
    //列印二維陣列長度
    fmt.Println(len(arr6[1])) //4
    //列印整個二維陣列
    fmt.Println(arr6)  //[[0 1 2 3] [6 7 9 0] [6 4 5 0]]
    
    arr7 := [...]string{1:"zhangsan", 6:"lisi", 3:"wangwu"}
    fmt.Printf("%q",arr7)  //["" "zhangsan" "" "wangwu" "" "" "lisi"]
}
package main
import "fmt"
func main() {
    var a = new([5]int)
    test(a)
    fmt.Println(a, len(a))
}
func test(a *[5]int) {
    a[1] = 5
}


///&[0 5 0 0 0] 5
package main
import "fmt"
func main() {
    a := [...]User{
        {0, "User0"},
        {8, "User8"},
    }
    b := [...]*User{
        {0, "User0"},
        {8, "User8"},
    }
    fmt.Println(a, len(a))
    fmt.Println(b, len(b))

}
type User struct {
    Id   int
    Name string
}

//結果
//[{0 User0} {8 User8}] 2
//[0xc042002440 0xc042002460] 2
//for range遍歷
package main
import (
    "fmt"
)


func main() {
    arr := [...]string{"golang", "php", "java", "python"}
    for key, val := range arr {
    //for _, val := range arr {  //如果不想利用key，可以用佔位符
        fmt.Printf("key=%v, val=%v\n", key, val)
    }
    // key=0, val=golang
    // key=1, val=php
    // key=2, val=java
    // key=3, val=python
}

 

相關文章