Advanced usage and techniques of Golang function parameter passing

Advanced usage of Go function parameter passing includes pointer passing and reference passing. Pointer passing passes a variable pointer to a function, allowing the function to modify the original variable directly. Pass-by-reference passes the variable itself to the function, avoiding unnecessary copying and directly modifying the original variable.

Advanced usage and techniques of Go function parameter passing

In the Go language, the default way of passing function parameters is value passing, which means passing to A copy of the function's variables will be copied inside the function. However, the Go language also provides pointer passing and reference passing, which can avoid unnecessary copy operations and allow functions to directly modify variables passed by the caller.

Pointer passing

The syntax of pointer passing is similar to value passing, except that you need to add a * symbol before the parameter type. Pointer passing passes the pointer of the argument (a value pointing to the memory address of the variable) to the function.

func Increment(n *int) {
    *n++ // 解引用指针并增加指向变量的值
}

Practical case:

Let us write a function Swap to exchange the values ​​of two integers. Swapping is not possible using pass-by-value because modifications made to the parameters inside the function do not affect the original variables passed by the caller. However, this can be done using pointer passing.

func Swap(a, b *int) {
    *a, *b = *b, *a // 解引用指针并交换值
}

func main() {
    x, y := 10, 20
    Swap(&x, &y) // 传递指针地址
    fmt.Println(x, y) // 输出：20 10
}

Passing by reference

Passing by reference is similar to passing by pointer, except that passing by reference does not copy the pointer, but directly passes the variable itself to the function. The syntax for passing by reference is the same as passing by pointer, but the * symbol is not preceded by the type.

Practical case:

Let us write a function UpdateSlice to update all elements in the slice. This cannot be accomplished efficiently using pass-by-value, since modifications to the slice inside the function do not affect the original slice passed by the caller. However, using pass-by-reference avoids unnecessary copying and directly modifies the original slice.

func UpdateSlice(s []int) {
    for i := range s {
        s[i]++ // 直接修改切片中的元素
    }
}

func main() {
    slice := []int{1, 2, 3}
    UpdateSlice(slice) // 传递引用
    fmt.Println(slice) // 输出：2 3 4
}

Summary

Go language provides three parameter passing methods: value passing, pointer passing and reference passing, which can meet the needs of different scenarios. Pointer passing and reference passing can avoid unnecessary copy operations and allow functions to directly modify variables passed by the caller. Choosing the appropriate parameter passing method can improve the efficiency and readability of the program.

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