Passing Arguments By Reference

<?php

  /*
    Function
    - Passing Arguments by Reference
    --- By Default, Function Arguments Are Passed By Value
    --- If The Value Of The Argument Inside The Function Changed It Will Not Change Outside
    --- To Change It Outside Pass The Argument By Reference

    - Return Type Declarations

    Search
    - PHP Strict Mode
  */

  function add_five(&#038;$number) {
    $number += 5;
    return $number;
  }

  $n = 15;

  echo add_five($n) . "<br>"; // 20

  echo $n; // 20

  echo '<br>';

  function calculate($n1, $n2) : int {
    return $n1 + $n2;
  }

  echo calculate(10.5, 9.5);

  echo '<br>';

  echo gettype(calculate(10.5, 9.5)); // Integer