Go Language Pointers as Function Parameters

Go Pointers

Go language allows passing pointers to functions by simply setting the function's parameter to a pointer type.

The following example demonstrates how to pass pointers to a function and modify the values inside the function after the call:

Example

package main

import "fmt"

func main() {
   /* Define local variables */
   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 )

   /* Call the function to swap values
   * &a points to the address of variable a
   * &b points to the 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      /* Assign y's value to x */
   *y = temp    /* Assign temp's value to y */
}

The output of the above example is:

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

Go Pointers