PHP str_rot13() Function Last Updated : 11 Jul, 2025 Comments Improve Suggest changes Like Article Like Report The function str_rot13() is a built-in function in php. This function accepts a string and shifts every alphabet present in the string by 13 places in the alphabet. The function leaves numeric and non-alphabetical characters untouched. By passing an encoded string as argument, the function will return the original string. Syntax: str_rot13 ( $string ) Parameter: This function accepts only a string parameter which can be observed from the above syntax. The description of the parameter is as follows. $string : This is the only mandatory parameter of the function. This parameter passes a string to the function which needs to be encoded. Return Value: The function returns the encoded string. Examples: Input : $string = "Geeks for Geeks" Output : Trrxf sbe Trrxf Input : $string = "Trrxf sbe Trrxf" Output : Geeks for Geeks Below program illustrate the str_rot13() function in PHP: php <?php echo str_rot13("Geeks for Geeks"); echo "\n"; echo str_rot13("Trrxf sbe Trrxf"); ?> Output: Trrxf sbe Trrxf Geeks for Geeks Reference: https://www.php.net/manual/en/function.str-rot13.php Comment GeeksforGeeks 0 Improve GeeksforGeeks 0 Improve Article Tags : Misc Web Technologies PHP PHP-string Explore PHP Tutorial 8 min read BasicsPHP Syntax 4 min read PHP Variables 5 min read PHP | Functions 8 min read PHP Loops 4 min read ArrayPHP Arrays 5 min read PHP Associative Arrays 4 min read Multidimensional arrays in PHP 5 min read Sorting Arrays in PHP 4 min read OOPs & InterfacesPHP Classes 2 min read PHP | Constructors and Destructors 5 min read PHP Access Modifiers 4 min read Multiple Inheritance in PHP 4 min read MySQL DatabasePHP | MySQL Database Introduction 4 min read PHP Database connection 2 min read PHP | MySQL ( Creating Database ) 3 min read PHP | MySQL ( Creating Table ) 3 min read PHP AdvancePHP Superglobals 6 min read PHP | Regular Expressions 12 min read PHP Form Handling 4 min read PHP File Handling 4 min read PHP | Uploading File 3 min read PHP Cookies 9 min read PHP | Sessions 7 min read Like