Hello,

I need a little help with preg_match / regexp, I want only a-z, A-Z (capitals) and 0-9 to be used in $str,

What I've got so far:

preg_match("[a-zA-Z0-9]", $str)

This doesn't work, and I'm not exactly a regexp whiz...

Try

PHP Code:

preg_match("/[a-zA-Z0-9]+/", $str) 


I would actually use:

PHP Code:

preg_match("/^[a-zA-Z0-9]+$/", $str) 


It seemed as though you wanted to only match those charactors in the set. If you don't add the ^ (beginning of string) and $ (end of string), then the pattern could match only a section of the string, and not the whole thing.

Pattern Syntax:
http://us3.php.net/manual/en/referen...ern.syntax.php

Good clarification, phpknowhow. I hardly ever use the ^ and $ symbols in regexs b/c I'm not that great at them in the first place. I really appreciate your explanation as to why using them benefits the expression.

Originally Posted by phpknowhow

I would actually use:

PHP Code:

preg_match("/^[a-zA-Z0-9]+$/", $str) 


It seemed as though you wanted to only match those charactors in the set. If you don't add the ^ (beginning of string) and $ (end of string), then the pattern could match only a section of the string, and not the whole thing.

Pattern Syntax:
http://us3.php.net/manual/en/referen...ern.syntax.php

Thanks that one worked.