Golang的数组初始化方式及for-range遍历

package main
import (
    "fmt"
)


func main() {
    var arr1 [3]int = [3]int{1, 2, 3} //定义并初始化长度为3的数组
    fmt.Println(arr1)  //[1 2 3]

    arr2 := [...] int {20:-1} //长度为20的数组，只有最后一个是-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}  //定义并初始化长度为3的数组
    fmt.Println(arr3) //[5 6 7]

    arr4 := [...]int{1:100, 3:50, 0:200}  //指定下标的数组，一共四个，因为最大是3
    fmt.Println(arr4) //[200 100 0 50]

    var arr5 [3]int   //3个int型的数组，初始值是3个0,数组“零值”状态
    fmt.Println(arr5) //[0 0 0]

    //二维数组
    arr6 := [3][4]int{{0,1,2,3},{6,7,9},{6,4,5}}
    //打印一维数组长度
    fmt.Println(len(arr6))  //3
    //打印二维数组长度
    fmt.Println(len(arr6[1])) //4
    //打印整个二维数组
    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
}

//结果
//[{0 User0} {8 User8}] 2
//[0xc042002440 0xc042002460] 2

//for range遍历
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，可以用占位符
        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
}