how to accept input with only alphabet, numeric, hypen and underscore?

[markthien]

Hi guys,

 

  I need to check if user enter only alphabet, numeric, hypen and underscore like "mark_thien-01", "markthien" or "mark0" or "mark_1" is valid. Appreciate any help please.

 

Thanks & Regards,

Mark Thien

[charleshill]

$data = ereg_replace('[^a-zA-Z0-9_-]', '', $data);