I want in detail how to use functions for checking regular expressions...kinda confused there...thanks

Am Sorry brother but you need to get indepth knowledge with Regular Expression first before using PCRE Function in PHP, try this.
http://www.noupe.com/php/php-regular-expressions.html

This is something you must learn on your own to understand its very confusing.

pc guru: Am Sorry brother but you need to get indepth knowledge with Regular Expression first before using PCRE Function in PHP, try this.
http://www.noupe.com/php/php-regular-expressions.html

This is something you must learn on your own to understand its very confusing.

Not a "brother". Thanks anyways

The easy way is that Regular Expression uses the Expression you pass to check against the String and return items that have met the Criteria. e.g

preg_match('/^hello/i', $test_string);

in Regular Expression "/" is used to surround the expression even in javaScript they are called RegExp Objects, "^" means it must start with a character followed after it, and "i" means case insensitive and the "g" would also mean Global.
	

so that code will match hello exactly

preg_match('/^[A-Za-z0-9]{5}/', $test_string); The "[]" will catch a set of characters mean A-Za-z to 0-9 

This will catch any Alphanumerical characters except whitespace and . that are at least five characters, the link i sent was one of the easiet i have encountered,also download the PHP Manual a lot of examples are there.