How to Calculate the Date Difference in PHP?

Introduction to Calculating the Date Difference in PHP

Finding the difference between two dates is frequently critical when working with dates in PHP, whether for event scheduling, age calculation, or data analysis. Days, weeks, months, or years are only a few possible units to assess this disparity in. For this common task, PHP, fortunately, provides a variety of approaches and functions. In this article, we'll look at the three most common methods that will give us the ability to calculate date discrepancies quickly and accurately.

We may increase the functionality and adaptability of our PHP apps by becoming familiar with these strategies. Having the ability to calculate date differences accurately is crucial, whether we are developing a booking system that must determine the amount of time between check-in and check-out dates or putting in place a subscription management system that determines how much time is left on a user's subscription.

Using date differences has a lot of use cases such as calculating age, determining payment due dates, or tracking subscription periods. Providing a lot of methods to perform these operations makes PHP a very useful language.

Method 1: Date Difference Based on Timestamp Values

Utilizing timestamp values is one method of calculating the date difference. Timestamps show the duration in seconds since January 1st, 1970, at 00:00:00 UTC. We may easily do mathematical operations to get the appropriate result by turning the dates to timestamps.

To transform dates into timestamps and determine the date difference in PHP, use the strtotime() function. These timestamps can then be used to do calculations to get the appropriate date difference. By subtracting the two dates' timestamps, we can determine the amount of time between them. We can ultimately format the result to suit our requirements. This technique allows us to work with precise numbers and determine the date difference in PHP.

Example

Here's an example that illustrates this method:

Output

Explanation

In this example, we calculate the difference between January 1, 2022, and June 12, 2023. We first convert the dates to timestamps using strtotime(), then perform the necessary calculations to obtain the number of years, months, and days between the two dates.

Limitations

This approach depends on executing mathematical calculations and converting dates to timestamps. One drawback is that it might not properly account for leap years or changes to daylight saving time. Since timestamps are based on seconds, alterations brought on by daylight saving time or leap years may have an impact on how accurately the estimated date difference is determined.

Method 2: Using the Date-Time Mathematical Formula

The date-time formula can also be used to determine the date difference in PHP. This approach accounts for leap years and the various monthly day counts. To get the desired outcome, the earlier date must be subtracted from the later date.

The PHP DateTime class can be used to implement this method. This class offers useful methods for calculating dates and gaining access to the required information. We can quickly implement this method and get precise results for our date difference calculations in PHP by utilizing the features of the DateTime class.

Example

Here's an example that demonstrates this method:

Output

Explanation
In this example, the dates January 1, 2022, and June 12, 2023, are represented by two DateTime objects. The DateTime class's diff() method is then used to determine how different the two dates are from one another. The DateInterval object that this method produces enables us to determine how many years, months, and days there are between the two dates.

Limitations

Manually calculating the difference between two dates using the date-time mathematical formula can be tricky and error-prone. In order to calculate the time between the dates, this method uses mathematical processes, and hence has some drawbacks, particularly when working with different time zones or scenarios where the number of days in a month varies, as it does in February. Thus, this method is not useful while calculating date differences between different time zones, or also in the case of different regional calendar systems present around the world.

Method 3: PHP date_diff() Function

Utilizing PHP's built-in date_diff() function is the third technique. By doing all essential computations internally, this function streamlines the process of computing date differences.

Syntax

Parameters

• DateTimeInterface $date1 and DateTimeInterface $date2:
  The two dates we want to compute the difference between.
• bool $absolute (optional):
  The absolute difference between the dates will be returned if true is specified.
• The date_diff() function:
  produces a DateInterval object that shows how the two dates differ from one another. Then, we may get access to the different parts of the difference, including years, months, and days.

Return Value

A DateInterval object will be returned when we use PHP's date_diff() function to determine the difference between two dates. This object has a number of elements that highlight the interval between the dates. These elements include the interval's years (y), months (m), and days (d) components. We may quickly extract and use the precise information of the date difference for additional processing or display needs by gaining access to these components.

PHP Version

The date_diff() function was first introduced in PHP version 5.3.0, and has been a part of PHP ever since. However, we should be careful while working with older unsupported versions which are using the date_diff() function.

Example

Here's an example that demonstrates the usage of the date_diff() function:

Output

Explanation
In this example, the dates January 1, 2022, and June 12, 2023, are represented by two DateTime objects. The date_diff() function is then called with these objects as inputs, and it returns a DateInterval object. Finally, we display the difference's outcome after retrieving each of its component parts.

Limitations

Although useful for computing date discrepancies, the date_diff() method has a constraint specific to the PHP version. This function was added in PHP 5.3.0, thus it might not be available if we’re using an earlier version of PHP. Because of this, it’s essential to check the PHP version we’re using to guarantee that precise date calculations can be made using the date_diff() function.

Method 4: PHP DateTimeImmutable Class

When calculating date differences, using the DateTimeImmutable class has the benefit of maintaining the original dates and guaranteeing immutability. This class is perfect for situations when we wish to preserve the integrity of the original dates because it creates instances of DateTimeImmutable objects that cannot be modified once generated.

Example

Output

Explanation

In this example, we have two DateTimeImmutable objects, $date1 and $date2, representing two different dates. We use the diff() method to find the difference between these dates, which gives us a DateInterval object named $diff. We then access the days property of the DateTimeImmutable object to print the result to the console.

Limitations

Firstly, DateTimeImmutable objects cannot be directly modified as they are immutable and compatibility requires PHP versions 5.5.0 and higher. Also, there are limitations in timezone handling, and complex conversions may require additional functions or libraries. Moreover, performance may be impacted due to the creation of new DateTimeImmutable instances for each calculation compared to mutable DateTime objects.