This regexp matches for example that: 10+10 10,0+9,9 10,0+9 10+9,9 allowed operations are: +,-,/,*...

designed to work specifically with the parser of the python dateutil package

http://www.pelagodesign.com/blog/2009/05/20/iso-8601-date-validation-that-doesnt-suck/

An example of a regex to use when wanting to remove special characters from a string

Easiest Way to Use: $datetime = new DateTime(); $datetime->setTimestamp($timestamp); $datetime->modify($operator . $hours . ' seconds');

Easy US phone numbers