In the past, we’ve discussed incrementing and decrementing a variable and incrementing and decrementing a number by another number but did you know that we can also increment and decrement a string? You can use the shorthand operators ++ or -- to accomplish this. Please note that you can’t increment or decrement a string by another number, only with the shorthand operators.

$string = 'a';

while ($string != 'zzz')
{
	echo ++$string . "\n";
}

The above infinite loop will loop through incrementing the string which starts at lowercase a all the up to zzz. PHP follows the Perl convention for incrementing and decrementing strings, not the C convention would increment according to the ASCII values and not just alphanumerics.

Speaking of numerics, you can also increment and decrement a string that contains numbers which will increment both the alphabetic portion as well as the numeric portion:

$string = 'AA0';

while ($string != 'ZZZ9')
{
	echo ++$string . "\n";
}

Pretty cool stuff, but to be honest, I’ve never once used this before for anything I’ve ever built. I could see it perhaps being used to suggest a username when someone requests a username that’s already in the system. “Sorry john123 is already taken, would you like to use john124?” or something like that. If you’ve had to increment or decrement a string for something aside from a homework assignment, I’d love to hear about it, comment below!