PHP正则表达式数字加一个字母

Question

I'm trying to achieve validation for numeric input plus letter X or x. So far I have:

if(preg_match('/[^0-9xX]+$/', $data)) return 'error';

It correctly returns error for all cases EXCEPT a123. Have anyone idea why?

Answer 1

Use ^ at the start of regex to check if the complete string instead of sub-string.

if(preg_match('/^[0-9xX]+$/', $data))
    return 'error';