title: Get the timestamp of exactly one week ago in PHP?
body: <p>I need to calculate the timestamp of exactly 7 days ago using PHP, so if it's currently March 25th at 7:30pm, it would return the timestamp for March 18th at 7:30pm.</p>
  
  <p>Should I just subtract 604800 seconds from the current timestamp, or is there a better method?</p>