In-depth understanding of pass-by-value and pass-by-reference in Go language

There are two transfer mechanisms in Go language: pass-by-value: pass a copy of the parameter value, and changes to the copy will not affect the original value. Pass by reference: Pass a reference to the parameter value, allowing the function or method to modify the original value. Understanding these two mechanisms is critical to writing efficient, maintainable code because they affect the behavior and efficiency of your code.

In-depth understanding of pass-by-value and pass-by-reference in Go language

In Go language, two different transfer mechanisms are involved when passing parameters: pass-by-value and Pass reference. Understanding both mechanisms is crucial as it affects the behavior and efficiency of your code.

Passing by value

When passing by value, a copy of the parameter value is passed to the function or method. This means that any changes made to the copy will not affect the original value.

Code example:

func changeValue(value int) {
    value++ // value 副本增加 1
}

func main() {
    value := 5
    changeValue(value)
    fmt.Println(value) // 输出 5，原始值未更改
}

Pass by reference

When passing by reference, the reference of the parameter value is passed to the function or method. This allows a function or method to modify the original value.

Code example:

func changeReference(ptr *int) {
    *ptr++ // 对 *ptr 指向的值增加 1
}

func main() {
    value := 5
    changeReference(&value)
    fmt.Println(value) // 输出 6，原始值已更改
}

Practical case

Case 1: String

Usefmt.Sprintf() When passing a function, passing a value will not modify the original string, but passing a reference will:

Code example:

// 传值
fmt.Sprintf("foo") // 返回新字符串 "foo"，不影响原始字符串

// 传引用
s := "bar"
fmt.Sprintf(&s, "baz") // 修改 s 为 "baz"

Case 2: Slicing

Slices are reference types, so they are always passed by reference. Changes made to it affect the original slice:

Code example:

s := []int{1, 2, 3}
func modifySlice(slice []int) {
    slice[1] = 0
}
modifySlice(s)
fmt.Println(s) // 输出 [1, 0, 3]，原始切片已被修改

Performance considerations

Passing by reference generally results in higher performance Overhead because the function or method requires access to the underlying value. However, in some cases, passing by reference may be more efficient, such as when copying a large value (such as an array or structure) is impractical.

Conclusion

It is very important to understand pass-by-value and pass-by-reference in Go language because it can help you write efficient and maintainable code. Choosing the appropriate delivery mechanism based on the type of data and expected operations is critical.

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