Function arguments in Golang

In Golang , a function is a group of statements used to perform tasks, with an optional return value . Go supports two main ways to pass arguments: Pass by value and Pass by reference. Go uses pass by value by default.

Basic terms in passing parameters to functions:

• Actual parameters: The arguments passed to the function.
• Formal parameters: The parameters received by the function.

For example

package main
import "fmt"

// Cố gắng sửa đổi giá trị của num
func modify(num int) {
    num = 50
}

func main() {
    num := 20
    fmt.Printf("Before, num = %d\n", num)
    modify(num)
    fmt.Printf("After, num = %d\n", num)
}

In this example, numremains unchanged after the call modifybecause it is passed by value.

Syntax

func functionName(param Type) {
    // function body                                        # Gọi theo giá trị
}

func functionName(param *Type) {
    // function body                                       # Gọi theo tham chiếu
}

Call by value

In call-by-value, a copy of the actual parameter value is passed. Changes made in the function do not affect the original variable.

Syntax

func functionName(param Type) {
    // function body
}

For example:

package main
import "fmt"

// Chỉnh sửa giá trị của num
func modify(num int) {
    num = 50
}

func main() {
    num := 20
    fmt.Printf("Before, num = %d\n", num)
    modify(num)
    fmt.Printf("After, num = %d\n", num)
}

Result:

Before, num = 20
After, num = 20

The value remains the same, as changes inside modifydo not affect numthe outside main.

Function arguments in Golang

• Call by value
• Call by reference

Call by reference

In call-by-reference, a pointer to the actual parameter is passed, so any changes inside the function are reflected on the original variable.

Syntax

func functionName(param *Type) {
    // function body
}

For example:

package main
import "fmt"

// Chỉnh sửa giá trị của num qua tham chiếu
func modify(num *int) {
    *num = 50
}

func main() {
    num := 20
    fmt.Printf("Before, num = %d\n", num)
    modify(&num)
    fmt.Printf("After, num = %d\n", num)
}

Result

Before, num = 20
After, num = 50

Since numit is passed by reference, the command modifywill change its value, which is reflected in the command main.