Datetime Difference in PHP

Date and Time in PHP with Security Considerations - Part 4

Foreword: In this part of the series I talk about Datetime Difference in PHP.

By: Chrysanthus Date Published: 19 Jan 2019

Introduction

This is part 4 of my series, Date and Time in PHP. In this part of the series I talk about Datetime Difference in PHP. You should have read the previous parts of series before reaching here, as this is the continuation.

When you subtract two datetimes, you have an interval.

The date_create() Function
In simple terms, the syntax is:

 date_create([ string $time = "now" ])

The time is optional. When omitted, the current time is considered. I suggest you use the datetime format: yyyy-mm-dd hh:ii:ss e.g 2012-07-14 18:45:31 . You can omit the hh:ii:ss part.

This function returns a new DateTime instance or FALSE on failure. .

The DateInterval Class Synopsis
It is,

DateInterval {
/* Properties */
public integer $y ;
public integer $m ;
public integer $d ;
public integer $h ;
public integer $i ;
public integer $s ;
public float $f ;
public integer $invert ;
public mixed $days ;
/* Methods */
public __construct ( string $interval_spec )
public static DateInterval createFromDateString ( string $time )
public string format ( string $format )
}

Properties

y
 Number of years.

m
 Number of months.

d
 Number of days.

h
 Number of hours.

i
 Number of minutes.

s
 Number of seconds.

f
 Number of microseconds, as a fraction of a second.

invert
 Is 1 if the interval represents a negative time period and 0 otherwise. See DateInterval::format().

days
 If the DateInterval object was created by DateTime::diff(), then this is the total number of days between the start and end dates. Otherwise, days will be FALSE.

The date_diff() Function
The simple syntax is:

 DateInterval date_diff ( DateTimeInterface $datetime1 , DateTimeInterface $datetime2)

where $datetime1 and $datetime2 are objects.

Read and test the following code:

<?php

 $datetime1 = date_create('2009-10-28 00:00:00');
 $datetime2 = date_create('2012-07-14 18:45:31');
 $interval = date_diff($datetime1, $datetime2);

 echo 'No of years: ', $interval->y, ' ';
 echo 'No of months: ', $interval->m, ' ';
 echo 'No of days: ', $interval->d, ' ';
 echo 'No of hours: ', $interval->h, ' ';
 echo 'No of minutes: ', $interval->i, ' ';
 echo 'No of seconds: ', $interval->s, ' ';
 echo '0 if interval is +ve or 1 otherwise: ', $interval->invert, ' ';

?>

The output is:

 No of years: 2
 No of months: 8
 No of days: 16
 No of hours: 18
 No of minutes: 45
 No of seconds: 31
 0 if interval is +ve or 1 otherwise: 0

Adding and Subtracting Durations in PHP Datetime
Spellings of durations that PHP datetime functions would accept are:

sec, secs, second, seconds
min, mins, minute, minutes
hour, hours
day, days
weeks
fortnight, fortnights, forthnight, forthnights
month, months
year, years

The date_add() Function
This function adds a duration to datetime, and returns a datetime object. The syntax is:

 datetimeObj date_add($datetimeObject, durationObject);

Read and test the following code:

<?php

 $datetime = date_create('2012-07-14 18:45:31');
 date_add($datetime, date_interval_create_from_date_string('10 days'));
 echo date_format($datetime, 'Y-m-d H:i:s');

?>

Note the use of the date_interval_create_from_date_string() function that returns a duration object. Also note that use of the date_format() function.

The output is:

 2012-07-24 18:45:31

The date_sub() Function
This function subtracts a duration from datetime, and returns a datetime object. The syntax is:

 datetimeObj date_sub($datetimeObject, durationObject);

Read and test the following code:

<?php

 $datetime = date_create('2012-07-14 18:45:31');
 date_sub($datetime, date_interval_create_from_date_string('10 day'));
 echo date_format($datetime, 'Y-m-d H:i:s');

?>

Note the use of the date_interval_create_from_date_string() function that returns a duration object. Also note that use of the date_format() function.

The output is:

 2012-07-04 18:45:31

That is it for this part of the series. We stop here and continue in the next part.

Chrys

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Datetime Difference in PHP

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