切片append作用

一、
d := append(c, e...) d的长度如果没有超过c的容量，则共享数组。
否则，搬迁。
二、copy值拷贝。

package main

import "fmt"

func Repeat(s string, count int) string {
    b := make([]byte, len(s)*count)
    bp := copy(b, s)
    fmt.Println(bp)
    for bp < len(b) {
        copy(b[bp:], b[:bp])
        bp *= 2
    }
    return string(b)
}

func test2() {
    data := make([]int, 10, 20)
    data[0] = 1
    data[1] = 2
    fmt.Println("length:", len(data), ":", data)
    dataappend := make([]int, 10, 20)//len <=10 则   result[0] = 99 会 影响源Slice
    dataappend[0] = 1
    dataappend[1] = 2
    fmt.Println("length:", len(dataappend), ":", dataappend)
    result := append(data, dataappend...)
    result[0] = 99
    result[11] = 98
    data = append(data, 88)
    fmt.Println("length:", len(data), ":", data)
    fmt.Println("length:", len(result), ":", result)
    fmt.Println("length:", len(dataappend), ":", dataappend)


}

func main() {
    //str := Repeat("_", 50)
    //fmt.Println(str)

    //var a []int
    //a = []int{1, 2, 3, 4}
    //var b []int
    //b = make([]int, 4)
    //copy(b, a)
    //b[1] = 999
    //fmt.Println(b, a)
    //
    //
    //c := []int{5, 6, 7, 8}
    c := make([]int, 4, 6)
    c[0] = 5
    c[1] = 5
    c[2] = 5
    c[3] = 5
    e := make([]int, 2, 6)
    e[0] = 10
    e[1] = 11
    d := append(c, e...)
    d[1] = 888
    c[2] = 666
    fmt.Println(c, d)

    //test2()
}