PHP strrev() Function

Reversing a string is one of the most basic string operations and is used very frequently by developers and programmers. PHP comes with a built-in function to reverse strings.

The strrev() function is a built-in function in PHP and is used to reverse a string. This function does not make any change in the original string passed to it as a parameter. 

Syntax:

string strrev($inpString)

Parameter: This function accepts a single parameter $inpString. This parameter is a string and it specifies the string which we want to reverse. If a number is passed to it instead of a string, it will also reverse that number. 

Return Value: The strrev() function returns the reversed string or the number. It does not make any change to the original string or number passed in the parameter. 

Examples:  

Input : $string = "geeks" 
Output : skeeg 

Input : $string = 143 
Output : 341 

Below programs illustrate the strrev() function in PHP:

Program 1: PHP program to demonstrate the strrev() function when a string is passed.  

PHP

<?php
// PHP program to demonstrate the
// strrev() function when a string is passed

$str = "geeks";

// prints the reversed string
echo strrev($str);
?>

Output: 

skeeg

Program 2: PHP program to demonstrate the strrev() function when a number is passed.  

PHP

<?php
// PHP program to demonstrate the
// strrev() function when a number is passed

// passing number instead of string
$num = 134;

// prints the reversed number
echo strrev($num);
?>

Output: 

431

Reference: 
http://php.net/manual/en/function.strrev.php