When working with PHP, you may need to format DateInterval components using percent directives. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
date_interval_format: Percent tokens like %d and %a differ: %a is total days from a date difference when available.
What Is date_interval_format in PHP?
Format DateInterval components using percent directives. Percent tokens like %d and %a differ: %a is total days from a date difference when available.
Syntax:
date_interval_format(DateInterval $object, string $format): string
Parameters and return value: The signature above identifies the arguments and return type where the API has a single call. For topic guides, follow the sequence of calls in the examples. Always distinguish a returned value from an object or variable modified by reference.
Important: %a can be unknown for directly constructed intervals; %d is the component within the interval.
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
$interval = new DateInterval("P2DT3H");
echo date_interval_format($interval, "%d days, %h hours");
Output:
2 days, 3 hours
The code focuses on the main operation. Percent tokens like %d and %a differ: %a is total days from a date difference when available.
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
$start = new DateTimeImmutable("2026-01-01");
$end = new DateTimeImmutable("2026-01-10");
echo date_interval_format($start->diff($end), "%a days");
Output:
9 days
What changes? %a can be unknown for directly constructed intervals; %d is the component within the interval.
Practical Example: Applying It in an Application
Use the following separate example as a starting point for a small application task. Check any extension or environment requirements below before running it.
<?php
$intervals = [new DateInterval("P1D"), new DateInterval("P3DT4H")];
foreach ($intervals as $interval) {
echo date_interval_format($interval, "%d days and %h hours") . PHP_EOL;
}
Output:
1 days and 0 hours
3 days and 4 hours
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. Percent tokens like %d and %a differ: %a is total days from a date difference when available.
Important Behavior and Edge Cases
- Core behavior: Percent tokens like %d and %a differ: %a is total days from a date difference when available.
- Inputs and results: %a can be unknown for directly constructed intervals; %d is the component within the interval.
- Alternatives: DateInterval::format() is the corresponding object method.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
date_interval_format | Format dateinterval components using percent directives. |
| Related PHP approach | DateInterval::format() is the corresponding object method. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | %a can be unknown for directly constructed intervals; %d is the component within the interval. |
| Confusing this API with a related operation | DateInterval::format() is the corresponding object method. |
| Assuming output is identical across environments | Check return values and required extensions or versions. Use explicit locale, timezone or encoding settings when they affect the result. |
Key Takeaways
- date_interval_format helps you format DateInterval components using percent directives.
- Percent tokens like %d and %a differ: %a is total days from a date difference when available.
- %a can be unknown for directly constructed intervals; %d is the component within the interval.
Use date_interval_format when you need to format DateInterval components using percent directives. Start with the first example, compare the second, and adapt the practical example to your inputs. Confirm the return value and environment requirements before adding it to production code.