This topic is about Go – Call by value.
The call by value method of passing arguments to a function copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument.
By default, Go programming language uses call by value method to pass arguments. In general, this means that code within a function cannot alter the arguments used to call the function. Consider the function swap() definition as follows.
/* function definition to swap the values */
func swap(int x, int y) int {
var temp int
temp = x /* save the value of x */
x = y /* put y into x */
y = temp /* put temp into y */
return temp;
}
Now, let us call the function swap() by passing actual values as in the following example −
package main
import "fmt"
func main() {
/* local variable definition */
var a int = 100
var b int = 200
fmt.Printf("Before swap, value of a : %d\n", a )
fmt.Printf("Before swap, value of b : %d\n", b )
/* calling a function to swap the values */
swap(a, b)
fmt.Printf("After swap, value of a : %d\n", a )
fmt.Printf("After swap, value of b : %d\n", b )
}
func swap(x, y int) int {
var temp int
temp = x /* save the value of x */
x = y /* put y into x */
y = temp /* put temp into y */
return temp;
}
Put the above code in a single C file, and then compile and execute it. It will produce the following result −
Before swap, value of a :100 Before swap, value of b :200 After swap, value of a :100 After swap, value of b :200
It shows that there is no change in the values though they had been changed inside the function.
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