为什么GO中切片的内容未更改? [英] Why is the content of slice not changed in GO?

问题描述

我认为在GO语言中，切片是通过引用传递的.但是，为什么下面的代码不更改切片c的内容?我想念什么吗?谢谢你.

I thought that in GO language, slices are passed by reference. But why the following code doesn't change the content of slice c? Am I missing something? Thank you.

package main

import (
    "fmt"
)


func call(c []int) {
    c = append(c, 1)
    fmt.Println(c)
}

func main() {
    c := make([]int, 1, 5)
    fmt.Println(c)
    call(c)
    fmt.Println(c)
}

打印的结果是:

[0] [0 1] [0]

[0] [0 1] [0]

在我期待的时候

[0] [0 1] [0 1]

[0] [0 1] [0 1]

推荐答案

切片的长度保留在切片标头中，该标头未通过引用传递.您可以将切片视为包含指向数组的指针，长度和容量的结构.

The length of the slice is kept in the slice header which is not passed by reference. You can think of a slice as a struct containing a pointer to the array, a length, and a capacity.

当附加到切片时，您修改了数据数组中的索引1，然后增加了切片标头中的长度.返回时，主函数中的c的长度为1，因此打印了相同的数据.

When you appended to the slice, you modified index 1 in the data array and then incremented the length in the slice header. When you returned, c in the main function had a length of 1 and so printed the same data.

切片以这种方式工作的原因是，您可以使多个切片指向同一数据.例如:

The reason slices work this way is so you can have multiple slices pointing to the same data. For example:

x := []int{1,2,3}
y := x[:2] // [1 2]
z := x[1:] // [2 3]

所有这三个切片都指向同一基础数组中的重叠数据.

All three of those slices point to overlapping data in the same underlying array.

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