How to Calculate a PHP Date Difference

Finding the elapsed time between two dates is a common need in Web applications.

Web application designers frequently need to calculate the time between two dates. PHP provides programmers with a built-in function for calculating date differences.

Significance

Use PHP's DateTime::diff to show how many days are left in the year.

Date difference calculations can be used for both fun and practical things. A programmer can display a count down to the next holiday or event, or can calculate the length of an outage.

Methodology

PHP provides two methods to calculate the difference between two dates. The first is an object-oriented method and the other is a procedural method. The object oriented methods looks like this:

public DateInterval DateTime::diff(DateTime $datetime1)

The procedural method is similar:

DateInterval date_diff (DateTime $datetime1, DateTime $datetime2)

Tips

Before running a date difference calculation, both dates must be in the same format. If the dates are stored in different formats, perform a conversion to the same format. Both methods support an optional parameter which allows you to return the absolute value of the difference. An absolute value removes the negative sign from the result, if there is one.

References

• PHP: DateTime::diff
• PHP F1: PHP Date Difference