PHP - Function Variable Functions

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Introduction

You can store the name of a function in a string variable, and use that variable instead of the function name when calling a function.

Here's an example:

Demo

<?php
$squareRoot ="sqrt";
echo"The square root of 9 is:". $squareRoot(9).". \n";
?>//w  w w.  j  av  a  2s .c  om

Result

The first line of code stores the function name, "sqrt", as a string in the $squareRoot variable.

This variable is then used in place of the function name on the second line.

Another example:

Demo

<?php

         $trigFunctions = array("sin","cos","tan");
         $degrees = 30;//from www  . j  a v a 2 s  .  c  o m

         foreach ($trigFunctions as $trigFunction) {
             echo"$trigFunction($degrees) =". $trigFunction(deg2rad($degrees))."\n";
          }
?>

Result

Here, the code creates an array of three built-in function names - "sin", "cos", and "tan" - and sets up a $degrees variable.

It loops through the array.

For each element, it calls the function whose name is stored in the element, passing in the value of $degrees converted to radians using PHP's built-in deg2rad() function), and displays the result.

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