Learning Programming Language

Welcome! PHP has nice built in date function which allows you to display dates in human readable formats.

<?php
 echo date("Y-m-d");
 echo date("Y/m/d");
 echo date("M d, Y");
 echo date("F d, Y");
 echo date("D M d, Y");
 echo date("l F d, Y");
 echo date("l F d, Y, h:i:s");
 echo date("l F d, Y, h:i A");
?>

2014-02-12
2014/02/12
Feb 12, 2014
February 12, 2014
Wed Feb 12, 2014
Wednesday February 12, 2014
Wednesday February 12, 2014, 02:15:12
Wednesday February 12, 2014, 02:15 PM

date(format, timestamp)

format - The first parameter, format, in the date function specifies how to display the date/time. It uses different letters to represent the date and time. Some of the letters used above are described here.

For complete list of date/time format reference, click here.

timestamp - The second parameter, timestamp, is an optional parameter. Timestamp is the number of seconds since January 1, 1970 at 00:00:00 GMT. This is also known as the Unix Timestamp.

Using the 2nd timestamp parameter we can do things like say find exactly what date or day it was yesterday or a week ago or what date it will be 1 month from today.

There are two ways we can do that.

Let's see some of the examples to find out dates using date and strtotime function.

<?php

echo "yesterday was ".date("Y-m-d", strtotime("-1 days"));

?>

yesterday was 2014-02-11

<?php

echo "1 week form today was ".date("Y-m-d", strtotime("-1 weeks"));

?>

1 week form today was 2014-02-05

<?php

echo "1 month from today will be ".date("Y-m-d", strtotime("+1 months"));

?>

1 month form today will be 2014-03-12

mktime could be used to find more specific things like find the next leap year in the calendar.

<?php

$day = "";

/*
 * since leap year falls ever 4 years so loop for 4 times 
 */
for($i=0; $i<4; $i++)
{
 //get day timestamp for feburary 29 for this year
 $day =  date("d", mktime(0, 0, 0, 2, 29, date("Y")+$i));
 
 /*
  * check if day equals 29. 
  * If day is 29 then it must be the leap year. if day is 01, then it not a leap year.
  */
 if($day == 29)
 {
  $year = date("Y")+$i;
  break;
 }
}

echo "next leap year is in year $year";
 
?>

next leap year is in year 2016

The mktime takes 6 arguments. The parameters are explained as below.