Go- 切片的使用

package main
import (	"fmt")
func printDivider(str ...string) {	fmt.Println()	fmt.Println("-----------------------------------------------")	if len(str) > 0 {		fmt.Println(str)	}}
func main() {	/*	   for range 用于一维数组和切片	*/	printDivider("for range 用于数组和切片")	s := []int{1, 2, 3}	for ix, value := range s { // ix 为索引值，value 为索引位置的值，他们都是作用域在 for 中的局部变量，value 是 s 中值的一个拷贝，不能用来修改 s 里元素的值		fmt.Printf("ix = %d, value = %d\n", ix, value) // 输出：ix = 0, value = 1 ...	}
	for ix := range s { // 忽略第二个参数		fmt.Printf("ix = %d\n", ix)	}
	for _, value := range s { // 忽略第一个参数		fmt.Printf("value = %d\n", value)	}
	items := [...]int{10, 20, 30}	fmt.Println(len(items), cap(items))
	/*	   for range 用于多维数组和切片	*/	printDivider("for range 用于多维数组和切片")	ss := [][]string{{"Hello", "World"}, {"I", "Have", "a", "Dream"}}	for row := range ss {		for column := range ss[row] {			fmt.Println(ss[row][column])		}	}
	/*	   切片扩缩容	*/	printDivider("切片扩缩容")	s1 := make([]int, 5, 10)	fmt.Println(s1)                                                // 输出：[0 0 0 0 0]	fmt.Printf("len(s1) = %d, cap(s1) = %d\n\n", len(s1), cap(s1)) // 输出：len(s1) = 5, cap(s1) = 10
	s1 = s1[0 : len(s1)+1]	fmt.Println(s1)                                                // 输出：[0 0 0 0 0 0]	fmt.Printf("len(s1) = %d, cap(s1) = %d\n\n", len(s1), cap(s1)) // 输出：len(s1) = 6, cap(s1) = 10
	s1 = s1[0 : len(s1)-1]	fmt.Println(s1)                                                // 输出：[0 0 0 0 0]	fmt.Printf("len(s1) = %d, cap(s1) = %d\n\n", len(s1), cap(s1)) // 输出：len(s1) = 5, cap(s1) = 10
	s1 = s1[0:cap(s1)]	fmt.Println(s1)                                                // [0 0 0 0 0 0 0 0 0 0]	fmt.Printf("len(s1) = %d, cap(s1) = %d\n\n", len(s1), cap(s1)) // len(s1) = 10, cap(s1) = 10
	//s1 = s1[-1:0] // 编译错误：invalid slice index -1 (index must be non-negative)	//s1 = s1[0 : cap(s1)+1] // 编译错误：panic: runtime error: slice bounds out of range [:11] with capacity 10
	/*	   切片的拷贝和追加	*/	printDivider("切片的拷贝和追加")	s11 := make([]int, 5, 10)	s12 := []int{1, 2, 3}	fmt.Printf("Copy Before: s11 = %v, s12 = %v\n", s11, s12) // 输出：Copy Before: s11 = [0 0 0 0 0], s12 = [1 2 3]	cnt := copy(s11, s12)                                     // 覆盖拷贝，返回拷贝的元素个数	fmt.Printf("Copy After : s11 = %v, s12 = %v\n", s11, s12) // 输出：Copy After : s11 = [1 2 3 0 0], s12 = [1 2 3]	fmt.Printf("Copy Return = %d\n", cnt)                     // 输出：Copy Return = 3
	fmt.Printf("Append Before: s11 = %v\n", s11) // 输出：Append Before: s11 = [1 2 3 0 0]	s11 = append(s11, 4, 5)                      // 添加元素之后未超过容量	fmt.Printf("Append After : s11 = %v\n", s11) // 输出：Append After : s11 = [1 2 3 0 0 4 5]
	s11 = append(s11, 6, 7, 8, 9, 10, 11)        // 添加元素之后超过容量，append会分配新的切片保证新增元素的存储，返回的切片指向的数组已经和之前不同	fmt.Printf("Append After : s11 = %v\n", s11) // 输出：Append After : s11 = [1 2 3 0 0 4 5 6 7 8 9 10 11]}