When working with PHP, you may need to format a DateTimeInterface using PHP tokens. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
date_format: Format tokens control date output; they are different from IntlDateFormatter patterns.
What Is date_format in PHP?
Format a DateTimeInterface using PHP tokens. Format tokens control date output; they are different from IntlDateFormatter patterns.
Syntax:
date_format(DateTimeInterface $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: Uppercase and lowercase format characters mean different things. Formatting does not modify the underlying instant.
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
$date = new DateTimeImmutable("2026-10-16", new DateTimeZone("UTC"));
echo date_format($date, "Y-m-d");
Output:
2026-10-16
The code focuses on the main operation. Format tokens control date output; they are different from IntlDateFormatter patterns.
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
$date = new DateTimeImmutable("2026-10-16 17:45", new DateTimeZone("UTC"));
echo date_format($date, "d/m/Y H:i");
Output:
16/10/2026 17:45
What changes? Uppercase and lowercase format characters mean different things. Formatting does not modify the underlying instant.
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
$date = new DateTimeImmutable("2026-10-16 17:45", new DateTimeZone("UTC"));
foreach (["Y-m-d", "d/m/Y", DATE_ATOM] as $format) {
echo date_format($date, $format) . PHP_EOL;
}
Output:
2026-10-16
16/10/2026
2026-10-16T17:45:00+00:00
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. Format tokens control date output; they are different from IntlDateFormatter patterns.
Important Behavior and Edge Cases
- Core behavior: Format tokens control date output; they are different from IntlDateFormatter patterns.
- Inputs and results: Uppercase and lowercase format characters mean different things. Formatting does not modify the underlying instant.
- Alternatives: DateTimeInterface::format() is the object-oriented form.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
date_format | Format a datetimeinterface using php tokens. |
| Related PHP approach | DateTimeInterface::format() is the object-oriented form. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | Uppercase and lowercase format characters mean different things. Formatting does not modify the underlying instant. |
| Confusing this API with a related operation | DateTimeInterface::format() is the object-oriented form. |
| 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_format helps you format a DateTimeInterface using PHP tokens.
- Format tokens control date output; they are different from IntlDateFormatter patterns.
- Uppercase and lowercase format characters mean different things. Formatting does not modify the underlying instant.
Use date_format when you need to format a DateTimeInterface using PHP tokens. 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.