Test if a regular expression is a valid one in PHP

Question

I am writing a form validation class and wish to include regular expressions in the validation. Therefore, the regex provided isn\'t guaranteed to be valid.

How can

Answer 1

Anyone still looking at this question anno 2018, and is using php 7, should be using try/catch.

try { 
    preg_match($mypattern, '');
} catch (\Throwable $exception) {
    // regex was invalid and more info is in $exception->getMessage()
}