slice
slice的本质是一个三元组(数组地址,长度,容量)
一个例子
package main
import (
"fmt"
)
func test(input []int) []int{
// input: 0x40c110->{address, 4, 4}
fmt.Printf("Slice inside address: %p\n", &input)
// input: 0x40c110->{address, 4, 4},但对address的修改影响到了val:0x40c0e0->{address, 4, 4}
input[0] = -1
input = append(input, 5)
// input: 0x40c110->{address, 5, 8},但val仍然为0x40c0e0->{address, 4, 4}
fmt.Println(input, len(input), cap(input))
return input
}
func main() {
// val:0x40c0e0->{address, 4, 4}
val := []int{1, 2, 3, 4}
fmt.Printf("Slice outside address: %p\n", &val)
fmt.Println(val, len(val), cap(val))
copyVal := test(val)
fmt.Printf("Slice outside address: %p\n", &val)
fmt.Println(val, len(val), cap(val))
fmt.Printf("CopySlice address: %p\n", ©Val)
fmt.Println(copyVal, len(copyVal), cap(copyVal))
}
结果:
Slice outside address: 0x40c0e0
[1 2 3 4] 4 4
Slice inside address: 0x40c110
[-1 2 3 4 5] 5 8
Slice outside address: 0x40c0e0
[-1 2 3 4] 4 4
CopySlice address: 0x40c100
[-1 2 3 4 5] 5 8
结论:
传入的是slice三元组的值拷贝,返回的slice三元组值拷贝给外部变量