How to pass reference in golang

In golang, all function parameters are passed by value, which means that if we want to change the value of the function parameter, we can only do it by passing a pointer. This is in line with golang's safe and simple design philosophy.

However, in some cases, we do need to pass a pointer to a pointer, that is, pass the address of a variable so that the variable can be modified. In this case, we use pass by reference.

Pass pointer

In golang, we can pass the address by declaring the parameter of the function as a pointer. For example, the following code passes the address of an int type variable:

func Increment(val *int) {
    *val++
}

func main() {
    num := 1
    Increment(&num)
    fmt.Println(num) // 输出 2
}

In this example, the Increment function receives parameters through a pointer and can modify the value of the passed variable. In the main function, we call the Increment function and pass it the address of num. Since the Increment function receives a pointer to an int variable, the function can change the value of num by dereferencing it (*val) and incrementing the variable.

Passing through pointers is the most common way to pass references in golang.

Passing pointer to pointer

In some cases, we need to modify the value of a pointer variable in a function. At this time, we will use the method of passing pointer to pointer.

For example, the following code demonstrates how to modify a variable by passing a pointer to a pointer:

func Increment(val **int) {
    **val++
}

func main() {
    num := 1
    p := &num
    Increment(&p)
    fmt.Println(num) // 输出 2
}

In this example, we first define a pointer variable p that points to type int, and then Pass its address to the Increment function. The Increment function receives a pointer to a pointer, that is, it receives a pointer to a pointer variable. In the function, we can use the dereference operator (**val) to increase the value of the variable pointed to by the p pointer, which is the value of the num variable.

It should be noted that in this case, the variable passed must be a pointer variable, otherwise the program will crash.

Conclusion

In golang, all function parameters are passed by value, that is, the value of the variable is copied to the parameter of the function. If we need to modify the value of a variable, we can do so by passing a pointer. If we need to modify the value of a pointer variable, we need to use the method of passing pointer to pointer.

In golang, the use of pointers and references is very convenient, but you need to pay attention to memory management and the life cycle of pointers, otherwise it may cause program instability and memory leaks. Therefore, when writing golang code, you need to pay attention to the correct use and management of pointers and references.

The above is the detailed content of How to pass reference in golang. For more information, please follow other related articles on the PHP Chinese website!