Regex for 2 letters followed by 4 digits

Question

The string should begin with \"S2\" followed by any 4 digits.

A matching string is \"S20165\".

I\'m trying with the following code, but it always echos OK ev

Answer 1

You have to use anchors:

/^S2[0-9]{4}$/

^ matches the start of the string and $ matches the end of the string, so this will make sure that you check the complete string and not just a substring.

You can also use \d instead of [0-9]. In PHP, as long as you do not use the 'u' pattern modifier, preg* functions are not Unicode aware, so the two are equivalent.