Go - Passing pointers to functions

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Go programming language allows you to pass a pointer to a function. To do so, simply declare the function parameter as a pointer type.

In the following example, we pass two pointers to a function and change the value inside the function which reflects back in the calling function −

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.
   * &a indicates pointer to a ie. address of variable a and 
   * &b indicates pointer to b ie. address of variable b.
   */
   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 *int, y *int) {
   var temp int
   temp = *x    /* save the value at address x */
   *x = *y      /* put y into x */
   *y = temp    /* put temp into y */
}

When the above code is compiled and executed, it produces the following result −

Before swap, value of a :100
Before swap, value of b :200
After swap, value of a :200
After swap, value of b :100