Variable scope in Golang functions: local variables and global variables

Local variables and global variables in Golang functions require specific code examples

In Golang, the scope of variables is a very important concept. In functions, we often encounter local variables and global variables. There are some differences between the two in scope and usage. Below I will introduce them in detail and give specific code examples.

Local variables are variables defined inside a function, and their scope is limited to the function to which they belong. Local variables only work inside the function and no longer exist after leaving the function. For example:

package main

import "fmt"

func main() {
    var a int = 10 // 局部变量
    var b int = 20 // 局部变量

    fmt.Printf("在main函数中，a=%d, b=%d
", a, b)
    test() // 调用test函数
}

func test() {
    var a int = 5 // 局部变量
    var b int = 15 // 局部变量

    fmt.Printf("在test函数中，a=%d, b=%d
", a, b)
}

Output result:

在main函数中，a=10, b=20
在test函数中，a=5, b=15

It can be seen from the output result that the values ​​of local variables a and b are different in the main function and test function. This is because they are defined in different functions and will not affect each other.

Corresponding to local variables are global variables. Global variables are variables defined outside the function and inside the package, and can be used throughout the package. The scope of a global variable starts at the point where it is defined and continues to the end of the package. The following is an example:

package main

import "fmt"

var a int = 10 // 全局变量

func main() {
    var b int = 20 // 局部变量
    fmt.Printf("在main函数中，a=%d, b=%d
", a, b)
    test() // 调用test函数
}

func test() {
    fmt.Printf("在test函数中，a=%d
", a)
}

Output result:

在main函数中，a=10, b=20
在test函数中，a=10

As can be seen from the output result, in the test function, although variable a is not defined, the value of global variable a can still be accessed . This is because global variables are visible throughout the package.

It should be noted that if there is a local variable with the same name as the global variable in the function, the local variable will overwrite the value of the global variable. For example:

package main

import "fmt"

var a int = 10 // 全局变量

func main() {
    var a int = 20 // 局部变量
    fmt.Printf("在main函数中，a=%d
", a)
    test() // 调用test函数
}

func test() {
    fmt.Printf("在test函数中，a=%d
", a)
}

Output result:

在main函数中，a=20
在test函数中，a=10

As can be seen from the output result, the value of a printed in the test function is the value of the global variable a, not the value of the local variable a .

To sum up, local variables and global variables can exist in functions in Golang. The scope of local variables is limited to within the function and no longer exists after leaving the function; while global variables are visible throughout the package and their values ​​can be accessed by any function. When a local variable and a global variable have the same name, the local variable will overwrite the value of the global variable. In actual programming, we can use local variables and global variables as needed to achieve more flexible and maintainable code.

The above are specific code examples of local variables and global variables in Golang functions. I hope it will be helpful for everyone to understand and use local variables and global variables.

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