How to round unix timestamp up and down to nearest half hour?

Question

Ok so I am working on a calendar application within my CRM system and I need to find the upper and lower bounds of the half an hour surrorunding the timestamp at which someb

Answer 1

As you probably know, a UNIX timestamp is a number of seconds, so substract/add 1800 (number of seconds in 30 minutes) and you will get the desired result.