go-切片操作

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 // Zero value for slice is nil

	for i := 0; i < 10; i++ {
		printSlice(s)
		s = append(s, 2*i+1)
	}
	fmt.Println(s)

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

	s2 := make([]int, 16)
	s3 := make([]int, 10, 32)
	printSlice(s2)
	printSlice(s3)

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

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

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

	fmt.Println(front)
	printSlice(s2)

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

	fmt.Println(tail)
	printSlice(s2)
}

运行结果：

Creating slice
[], len=0, cap=0
[1], len=1, cap=1
[1 3], len=2, cap=2
[1 3 5], len=3, cap=4
[1 3 5 7], len=4, cap=4
[1 3 5 7 9], len=5, cap=8
[1 3 5 7 9 11], len=6, cap=8
[1 3 5 7 9 11 13], len=7, cap=8
[1 3 5 7 9 11 13 15], len=8, cap=8
[1 3 5 7 9 11 13 15 17], len=9, cap=16
[1 3 5 7 9 11 13 15 17 19]
[2 4 6 8], len=4, cap=4
[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0], len=16, cap=16
[0 0 0 0 0 0 0 0 0 0], len=10, cap=32
Copying slice
[2 4 6 8 0 0 0 0 0 0 0 0 0 0 0 0], len=16, cap=16
Deleting elements from slice
[2 4 6 0 0 0 0 0 0 0 0 0 0 0 0], len=15, cap=16
Popping from front
2
[4 6 0 0 0 0 0 0 0 0 0 0 0 0], len=14, cap=15
Popping from back
0
[4 6 0 0 0 0 0 0 0 0 0 0 0], len=13, cap=15

总结：

添加元素时如果超越cap，系统会翻倍分配更大的底层数组