Regular_expression creation

Dear friends
New in field of Regular_expression

i want to find a string which contain this two things.
1) its should contain 'index.php?' at the start of string
2) it should contain article_id in string

Please help me how i can do it using Regular_expression

Thanks
In advance

Hello, i just don't know few things -

1. full string to match (index.php?article_id=123 - right page) ?
2. whats programming language you use - i dont know - so just giving you the regexp itself.

'/index.php\?article_id\=(.*?)/'