"range out of order in character class" in PHP regex?

Question

I am trying to get this work for a while but in vain. I want to create a php regex to check if a string has atleast one number and atleast one of the symbols amongst ( _-+=*& )

This is my regex

 $result = preg_match('/^(?=.*\d)(?=.*[_-+=*&]).{3,}$/',$pass);

I get the following error Warning: preg_match() [function.preg-match]: Compilation failed: range out of order in character class at offset 17 in myfile.php on line 8

any help ?

Answer 1

The - needs to be escaped, or placed at the start / end of the [...] list:

$result = preg_match('/^(?=.*\d)(?=.*[-_+=*&]).{3,}$/',$pass);

If you don't, - is interpreted as the range operator and if x > y in [x-y] you get that error.