String Increment

String increment is the PHP feature that applies the ++ pre- and post-increment operators on non-numeric strings.

These strings last character’s ASCII code is incremented by one, with possible extension of the string when the letters reach z and Z.

This feature, when based on ++ is deprecated, and shall be removed in PHP 9. It has been replaced by the str_increment() function, which has the same feature, though not implicit in the engine anymore. It is also extended with It has been replaced by the str_decrement().

A deprecation message is active since PHP 8.3.

<?php

$s = 'y';
echo ++$s; // z
echo ++$s; // aa
echo ++$s; // ab

$s = 'Y';
echo ++$s; // Z
echo ++$s; // AA
echo ++$s; // AA

?>

See also str_decrement and str_increment.

Related : Increment, String, American Standard Code for Information Interchange (ASCII), Type Juggling, Deprecation