允许字母，数字和某些字符删除其余[关闭]

Question

when user submit a form input text

i want it just to allow a-z 0-9 and -_ just this numbers digits and -_

how do i check the input and make it only this inputs allows and delete the rest

Thank You!

Answer 1

$output = preg_replace("/[^a-zA-Z0-9_\-]/", '', $input);