10.md

切片操作

向切片添加元素

arr ：= […]int{0, 1, 2, 3, 4, 5, 6, 7}
s1 := arr[2:6]
s2 := s1[3:5]
s3 := append(s2, 10)
s4 := append(s3, 11)
s5 := append(s4, 12)

• 添加元素时如果超越cap，系统会重新分配更大的底层数组；
• 由于值传递的关系，必须接收append的返回值；
• s = append(s, val)

package main
import "fmt"
func printSlice(s []int) {
    fmt.Printf("%v, len=%d, cap=%d\n", s, len(s), cap(s))
}


func main() {
    fmt.Println("Creating slice")
    var s []int // 定义空切片

    for i := 0; i < 100; i++ {
        printSlice(s)
        s = append(s, 2*i+1)
    }
    fmt.Println(s)

    s1 := []int{2, 4, 6, 8}
    printSlice(s1)

    s2 := make([]int, 16) // 知道切片元素len，且初始化值为0
    s3 := make([]int, 10, 32) // 知道切片元素len和cap，且初始化值为0

    printSlice(s2)
    printSlice(s3)

    // Copying slice
    fmt.Println("Copying slice")
    copy(s2, s1)
    printSlice(s2)

    // Deleting elements from slice
    fmt.Println("Deleting elements from slice")
    s2 = append(s2[:3], s2[4:]...)
    printSlice(s2)

    // Popping from front
    fmt.Println("Popping from front")
    front := s2[0]
    s2 = s2[1:]
    fmt.Println(front)
    printSlice(s2)

    // Popping from back
    fmt.Println("Popping from back")
    tail := s2[len(s2)-1]
    s2 = s2[:len(s2)-1]
    fmt.Println(tail)
    printSlice(s2)
}