How to change function content in golang

Golang is a programming language designed to solve various problems that arise when writing large programs. Golang has relatively simple syntax and powerful concurrency capabilities, making it widely used in fields such as web development and distributed systems. In Golang, various ways of manipulating data are provided. This article will focus on how to change the function content.

1. Modification of function parameters

In Golang, there are two ways to transfer function parameters: value transfer and pointer transfer. Passing by value means that a copy of the variable is passed, and modifications to the parameter in the function will not affect the original variable. Pointer passing means that the address of the variable is passed, and modifications to the parameter in the function will affect the original variable.

The sample code is as follows:

package main

import "fmt"

func main() {
    // 值传递
    x := 10
    modify(x)
    fmt.Println("x =", x)

    // 指针传递
    y := 10
    modifyByPointer(&y)
    fmt.Println("y =", y)
}

func modify(x int) {
    x = 20
}

func modifyByPointer(y *int) {
    *y = 20
}

The output result is:

x = 10
y = 20

It can be seen from the output result that value transfer will not change the value of the original variable, but pointer transfer will. The value of the original variable.

2. Modification of function return value

In Golang, a function can have multiple return values. If the function returns the value of a variable, modifications to the returned value within the function will not affect the original variable. However, if the function returns a pointer to a variable, modifications to the variable pointed to by the returned pointer within the function will affect the original variable.

The sample code is as follows:

package main

import "fmt"

func main() {
    x := 10
    y := modifyAndReturnPointer(&x)
    fmt.Println("x =", x)
    fmt.Println("y =", *y)
}

func modifyAndReturnPointer(x *int) *int {
    *x = 20
    return x
}

The output result is:

x = 20
y = 20

It can be seen from the output result that modifying the variable pointed to by the returned pointer inside the function will affect the original variable.

3. Modification when variables are used as function parameters

In Golang, functions can pass variables as parameters and modify the variables inside the function. If it is passed by value, then the modification of the variable inside the function will not affect the original variable; if it is passed by pointer, then the modification of the variable inside the function will affect the original variable.

The sample code is as follows:

package main

import "fmt"

type Person struct {
    name string
    age  int
}

func main() {
    p := Person{name: "Tom", age: 20}
    fmt.Println(p)
    modifyStruct(&p)
    fmt.Println(p)
}

func modifyStruct(p *Person) {
    p.age = 30
}

The output result is:

{Tom 20}
{Tom 30}

It can be seen from the output result that modifying the structure pointed to by the pointer inside the function will affect the original variable .

In short, in Golang, the way the variable is modified inside the function depends on the way the variable is passed. If it is passed by a pointer, then the modification of the variable inside the function will affect the original variable. Therefore, when writing a Golang program, you need to choose the appropriate delivery method and modification method according to the actual situation.

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