Detailed explanation of function parameter passing method in Go language

The Go language is an open source programming language developed by Google and is designed to improve developer productivity and code reliability. In the Go language, the way function parameters are passed is very important, as it can affect the performance and memory usage of the program.

1. Value passing

Value passing refers to copying the value of the parameter and passing it to the function. Operations on parameters inside the function will not affect the values ​​of external variables. Here is a simple value passing example:

package main

import "fmt"

func modifyValue(x int) {
    x = x * 2
    fmt.Println("Inside function:", x)
}

func main() {
    num := 10
    modifyValue(num)
    fmt.Println("Outside function:", num)
}

In the above example, the modifyValue function receives an integer parameter and multiplies the parameter by 2. After the function call, the value of the external variable num has not changed.

2. Passing by reference

Passing by reference means passing the address of the parameter to the function, and the function can modify the value of the external variable through the address. In the Go language, reference types such as slices, maps, and channels are passed by reference by default. Here is an example of passing by reference:

package main

import "fmt"

func modifySlice(s []int) {
    s[0] = 100
    fmt.Println("Inside function:", s)
}

func main() {
    slice := []int{1, 2, 3}
    modifySlice(slice)
    fmt.Println("Outside function:", slice)
}

In the above example, the modifySlice function receives a slice parameter and modifies the first element to 100. After the function call, the value of the outer slice slice has also changed.

3. Pass pointer

By passing the pointer of the parameter, the function can directly operate the value in the memory address pointed to by the parameter. This method can reduce the overhead of copying parameters, and is especially suitable for large data structures and situations that require frequent modifications. Here is an example of passing a pointer:

package main

import "fmt"

func modifyPointer(x *int) {
    *x = *x * 2
    fmt.Println("Inside function:", *x)
}

func main() {
    num := 10
    modifyPointer(&num)
    fmt.Println("Outside function:", num)
}

In the above example, the modifyPointer function receives an integer pointer parameter and multiplies the value pointed to by the pointer by 2. After the function call, the value of the external variable num has also changed.

Through the above examples, we can see the application and impact of different parameter passing methods in the Go language. In actual development, choosing the appropriate delivery method can improve the performance and maintainability of the program. I hope this article is helpful to readers, thank you for reading!

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