PHP - Call a function with no return that does actually change values

Question

I want to call a function in PHP, that changes existing variables without returning a specific one.

Here an example:

<?php
  $number1 = 5;
  $number2 = 3;
  echo $number1;
  echo $number2; //shows the unmodified numbers

  modifyNumbers($number1, $number2); // Modifies the Numbers

  echo $number1;
  echo $number2; //shows the modified numbers
?>

<!-- Stuff -->

<?php
  function modifyNumbers($number1, $number2) {
    /* Doing math stuff with the numbers */
    /* No return because many numbers were changed / overwritten
  }
?>

Basically, I want to make a function that is just overwriting variables instead of giving a specific value back to a specific variable where the function is called.

Thanks in advance!

Use the reference of the variables. – Sougata Bose Jul 08 '15 at 10:14 — Sougata Bose, Jul 08 '15 at 10:14
you need to define the variables as global – Vikas Umrao Jul 08 '15 at 10:17 — Vikas Umrao, Jul 08 '15 at 10:17
Define as global worked great, thanks! – Skalibran Jul 08 '15 at 10:22 — Skalibran, Jul 08 '15 at 10:22

score 4 · Accepted Answer · answered Jul 08 '15 at 10:19

pass by reference with &

<?php
  $number1 = 5;
  $number2 = 3;
  echo $number1;
  echo $number2; //shows the unmodified numbers

  modifyNumbers($number1, $number2); // Modifies the Numbers

  echo $number1;
  echo $number2; //shows the modified numbers
?>

<!-- Stuff -->

<?php
  function modifyNumbers(&$number1, &$number2) {
    $number1++;
    $number2--;
  }
?>

score 3 · Answer 2 · answered Jul 08 '15 at 10:19

3

Precede the arguments with an ampersand.

function modifyNumbers(&$number1, &$number2) {
    /* Doing math stuff with the numbers */
    /* No return because many numbers were changed / overwritten
  }

This way, a reference is created and everything you do with the variable will affect the variable 'outside' the function.

answered Jul 08 '15 at 10:19

Barry

3,683
1
18
25

Awesome, even shorter than define the variables as global :) – Skalibran Jul 08 '15 at 10:23

PHP - Call a function with no return that does actually change values

2 Answers2