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Website Programming in PHP / MYSQL
mktime
(PHP 4, PHP 5)
mktime — Get Unix timestamp for a date
Description
Returns the Unix timestamp corresponding to the arguments given. This timestamp is a long integer containing the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.
Arguments may be left out in order from right to left; any arguments thus omitted will be set to the current value according to the local date and time.
Parameters
- hour
-
The number of the hour.
- minute
-
The number of the minute.
- second
-
The number of seconds past the minute.
- month
-
The number of the month.
- day
-
The number of the day.
- year
-
The number of the year, may be a two or four digit value, with values between 0-69 mapping to 2000-2069 and 70-100 to 1970-2000. On systems where time_t is a 32bit signed integer, as most common today, the valid range for year is somewhere between 1901 and 2038. However, before PHP 5.1.0 this range was limited from 1970 to 2038 on some systems (e.g. Windows).
- is_dst
-
This parameter can be set to 1 if the time is during daylight savings time (DST), 0 if it is not, or -1 (the default) if it is unknown whether the time is within daylight savings time or not. If it's unknown, PHP tries to figure it out itself. This can cause unexpected (but not incorrect) results. Some times are invalid if DST is enabled on the system PHP is running on or is_dst is set to 1. If DST is enabled in e.g. 2:00, all times between 2:00 and 3:00 are invalid and mktime() returns an undefined (usually negative) value. Some systems (e.g. Solaris 8) enable DST at midnight so time 0:30 of the day when DST is enabled is evaluated as 23:30 of the previous day.
Note: As of PHP 5.1.0, this parameter became deprecated. As a result, the new timezone handling features should be used instead.
Return Values
mktime() returns the Unix timestamp of the arguments given. If the arguments are invalid, the function returns FALSE (before PHP 5.1 it returned -1).
Errors/Exceptions
Every call to a date/time function will generate a E_NOTICE if the time zone is not valid, and/or a E_STRICT message if using the system settings or the TZ environment variable. See also date_default_timezone_set()
ChangeLog
| Version | Description |
|---|---|
| 3.0.10 | Added is_dst parameter |
| 5.1.0 | The is_dst parameter became deprecated. Made the function return FALSE on error, instead of -1. Fixed the function to accept the year, month and day to be all passed as zero. |
| 5.1.0 | Now issues the E_STRICT and E_NOTICE time zone errors. |
Examples
Example #1 mktime() example
mktime() is useful for doing date arithmetic and validation, as it will automatically calculate the correct value for out-of-range input. For example, each of the following lines produces the string "Jan-01-1998".
<?php
echo date("M-d-Y", mktime(0, 0, 0, 12, 32, 1997));
echo date("M-d-Y", mktime(0, 0, 0, 13, 1, 1997));
echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 1998));
echo date("M-d-Y", mktime(0, 0, 0, 1, 1, 98));
?>
Example #2 Last day of next month
The last day of any given month can be expressed as the "0" day of the next month, not the -1 day. Both of the following examples will produce the string "The last day in Feb 2000 is: 29".
<?php
$lastday = mktime(0, 0, 0, 3, 0, 2000);
echo strftime("Last day in Feb 2000 is: %d", $lastday);
$lastday = mktime(0, 0, 0, 4, -31, 2000);
echo strftime("Last day in Feb 2000 is: %d", $lastday);
?>
Notes
Before PHP 5.1.0, negative timestamps were not supported under any known version of Windows and some other systems as well. Therefore the range of valid years was limited to 1970 through 2038.
