PHP Cookbook

3.9. Parsing Dates and Times from Strings

Problem

You need to get a date or time in a string into a format you can use in calculations. For example, you want to convert date expressions such as “last Thursday” into an epoch timestamp.

Solution

The simplest way to parse a date or time string is with strtotime( ) , which turns a variety of human-readable date and time strings into epoch timestamps:

$a = strtotime('march 10'); // defaults to the current year

Discussion

The grammar strtotime( ) uses is both complicated and comprehensive so the best way to get comfortable with it is to try out lots of different time expressions. If you’re curious about its nuts and bolts, check out ext/standard/parsedate.y in the PHP source distribution.

The function strtotime( ) understands words about the current time:

$a = strtotime('now');
print strftime('%c',$a);
$a = strtotime('today');
print strftime('%c',$a);
Mon Aug 12 20:35:10 2002
               Mon Aug 12 20:35:10 2002

It understands different ways to identify a time and date:

$a = strtotime('5/12/1994');
print strftime('%c',$a);
$a = strtotime('12 may 1994');
print strftime('%c',$a);
Thu May 12 00:00:00 1994
               Thu May 12 00:00:00 1994

It understands relative times and dates:

$a = strtotime('last thursday');   // On August 12, 2002
print strftime('%c',$a);
$a = strtotime('2001-07-12 2pm + 1 month');
print strftime('%c',$a);
Thu Aug  8 00:00:00 2002
               Mon Aug 12 14:00:00 2002

It understands time zones. When the following is run from a computer in EDT, it prints out ...