Please consider the following code:

PHP Code:
var_dump(filter_var('a=b@test.com',  FILTER_VALIDATE_EMAIL)); 
Ideally the above email should be invalid and var_dump should return false but the strange thing is when u run this code on the following sites they return non similar results, can anyone tell me whats going on?

Site: http://codepad.org/MtDCoxxZ
Output: false

Site: http://writecodeonline.com/php/
Output: True