go语言基础之切片的创建和截取

1、切片的创建

示例：

package main //必须有个main包

import "fmt"

func main() {
        //切片和数组的区别
        //数组[]里面的长度时固定的一个常量， 数组不能修改长度， len和cap永远都是5
        a := [5]int{}
        fmt.Printf("len = %d, cap = %d\n", len(a), cap(a))

        //切片， []里面为空，或者为...，切片的长度或容量可以不固定
        s := []int{}
        fmt.Printf("1: len = %d, cap = %d\n", len(s), cap(s))

        s = append(s, 11) //给切片末尾追加一个成员
        fmt.Printf("append: len = %d, cap = %d\n", len(s), cap(s))

}

执行结果：

len = 5, cap = 5
1: len = 0, cap = 0
append: len = 1, cap = 1  

2、切片的截取

切片语法：

示例:

package main //必须有个main包

import "fmt"

func main() {

   array := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

   //[low:high:max] 取下标从low开始的元素， len=high-low, cap=max-low

   s1 := array[:] //[0:len(array):len(array)] 不指定容量和长度一样

   fmt.Println("s1 = ", s1)

   fmt.Printf("len = %d, cap = %d\n", len(s1), cap(s1))

   //操作某个元素，和数组操作方式一样

   data := array[1]

   fmt.Println("data = ", data)

   s2 := array[3:6:7] //a[3], a[4], a[5]   len = 6-3=3    cap = 7-3=4

   fmt.Println("s2 = ", s2)

   fmt.Printf("len = %d, cap = %d\n", len(s2), cap(s2))

   s3 := array[:6] //从0开始，去6个元素，容量也是6， 常用

   fmt.Println("s3 = ", s3)

   fmt.Printf("len = %d, cap = %d\n", len(s3), cap(s3))

   s4 := array[3:] //从下标为3开始，到结尾

   fmt.Println("s4 = ", s4)  //[3 4 5 6 7 8 9]

   fmt.Printf("len = %d, cap = %d\n", len(s4), cap(s4))

}

执行结果：

s1 = [0 1 2 3 4 5 6 7 8 9]

len = 10, cap = 10

data = 1

s2 = [3 4 5]

len = 3, cap = 4

s3 = [0 1 2 3 4 5]

len = 6, cap = 10

s4 = [3 4 5 6 7 8 9]

len = 7, cap = 7