Calling a Function by Name in PHP

Let's say you have a string with a function name stored in a variable. Using this variable, you can call the function whose name is stored in that variable.

Let's look at an example. Suppose we have the following function:

php<?php
  function func($num)
  {
    echo $num ** 2;
  }
?>

Let's also assume we have a variable with the name of this function:

php<?php
  $name = 'func';
?>

Let's call the function by its name. To do this, we write the variable containing the function name and put parentheses for the call after it:

php<?php
  $name(3); // 9
?>

php<?php
  $name = 'sqrt';
?>