# DateInterval::format

(PHP 5 >= 5.3.0, PHP 7)

DateInterval::format — Formats the interval

### Description

public DateInterval::format ( string `$format` ) : string

Formats the interval.

### Parameters

`format`

  The following characters are recognized in the `format` parameter string. Each format character must be prefixed by a percent sign (%).
  `format` character | Description | Example values
  --- | --- | ---
  % | Literal % | %
  Y | Years, numeric, at least 2 digits with leading 0 | 01, 03
  y | Years, numeric | 1, 3
  M | Months, numeric, at least 2 digits with leading 0 | 01, 03, 12
  m | Months, numeric | 1, 3, 12
  D | Days, numeric, at least 2 digits with leading 0 | 01, 03, 31
  d | Days, numeric | 1, 3, 31
  a | Total number of days as a result of a DateTime::diff() or (unknown) otherwise | 4, 18, 8123
  H | Hours, numeric, at least 2 digits with leading 0 | 01, 03, 23
  h | Hours, numeric | 1, 3, 23
  I | Minutes, numeric, at least 2 digits with leading 0 | 01, 03, 59
  i | Minutes, numeric | 1, 3, 59
  S | Seconds, numeric, at least 2 digits with leading 0 | 01, 03, 57
  s | Seconds, numeric | 1, 3, 57
  F | Microseconds, numeric, at least 6 digits with leading 0 | 007701, 052738, 428291
  f | Microseconds, numeric | 7701, 52738, 428291
  R | Sign "-" when negative, "+" when positive | -, +
  r | Sign "-" when negative, empty when positive | -,

### Return Values

Returns the formatted interval.

### Notes

> Note:

> The DateInterval::format() method does not recalculate carry over points in time strings nor in date segments. This is expected because it is not possible to overflow values like "32 days" which could be interpreted as anything from "1 month and 4 days" to "1 month and 1 day".

### Changelog

Version | Description
--- | ---
7.1.0 | The F and f format characters were added.

### Examples

Example #1 DateInterval example

`<?php
$interval = new DateInterval('P2Y4DT6H8M');
echo $interval->format('%d days');
?>`

The above example will output:

    4 days

Example #2 DateInterval and carry over points

`<?php
$interval = new DateInterval('P32D');
echo $interval->format('%d days');
?>`

The above example will output:

    32 days

Example #3 DateInterval and DateTime::diff() with the %a and %d modifiers

`<?php
$january = new DateTime('2010-01-01');
$february = new DateTime('2010-02-01');
$interval = $february->diff($january);
// %a will output the total number of days.
echo $interval->format('%a total days')."\n";
// While %d will only output the number of days not already covered by the
// month.
echo $interval->format('%m month, %d days');
?>`

The above example will output:

    31 total days
    1 month, 0 days

### See Also

- DateTime::diff() - Returns the difference between two DateTime objects