PHP date_isodate_set() Function

The PHP date_isodate_set() function sets the date of a DateTime object, according to the ISO 8601 standard - using weeks and day offsets rather than specific dates. This function is an alias of DateTime::setISODate() method.

Syntax

//Object-oriented style
public DateTime::setISODate(year, week, dayOfWeek)

//Procedural style
date_isodate_set(object, year, week, dayOfWeek)

Parameters

`object`	`Required.` For procedural style only: A DateTime object returned by date_create().
`year`	`Required.` Specify an integer value representing year of the date.
`week`	`Required.` Specify an integer value representing week of the date.
`dayOfWeek`	`Optional.` Specify an integer value representing the day of the week. Default is 1.

Return Value

Returns the DateTime object with modified date on success, otherwise returns false.

Example: using both styles

The example below shows the usage of date_isodate_set() function.

<?php
  //creating a DateTime object
  $date = date_create();

  //setting date using Object-oriented style
  $date->setISODate(2015, 10, 2); 

  //formatting the datetime to print it
  echo date_format($date, "d-M-Y")."\n";

  //setting date using Procedural style
  date_isodate_set($date, 2015, 11, 2); 

  //formatting the datetime to print it
  echo date_format($date, "d-M-Y")."\n";
?>

The output of the above code will be:

03-Mar-2015
10-Mar-2015

Example: Modifying date of a DateTime object

This function can be used to modify date of the DateTime object to a new value. Consider the example below:

<?php
  //datetime string
  $datetime_string = "14-May-2015";

  //creating a DateTime object
  $date = date_create($datetime_string);

  //formatting the datetime to print it
  echo "Original date: ".date_format($date, "d-M-Y")."\n";

  //setting date to a new value
  date_isodate_set($date, 2016, 10, 4); 

  //formatting the datetime to print it
  echo "Modified date: ".date_format($date, "d-M-Y")."\n";
?>

The output of the above code will be:

Original date: 14-May-2015
Modified date: 10-Mar-2016

Example: Adding values exceeding ranges

When values exceeding ranges are passed to this function, they will be added to their parent values. Consider the example below:

<?php
  //creating a DateTime object
  $date = date_create();

  //setting date to a new value
  date_isodate_set($date, 2001, 10, 2);
  echo date_format($date, 'd-M-Y') . "\n";

  //setting date with exceeding range of dayOfWeek -
  //exceeding days (2 days) will be added 
  date_isodate_set($date, 2001, 10, 9);
  echo date_format($date, 'd-M-Y') . "\n";

  //setting date with exceeding range of week -
  //exceeding weeks (3 weeks) will be added
  date_isodate_set($date, 2001, 55, 2);
  echo date_format($date, 'd-M-Y') . "\n";
?>

The output of the above code will be:

06-Mar-2001
13-Mar-2001
15-Jan-2002

Example: Finding the month a week is in

The example below illustrates on finding the month a week is in.

<?php
  //creating a DateTime object
  $date = new DateTime();

  //setting date to a new value
  date_isodate_set($date, 2001, 10);

  //finding the month the week is in
  echo date_format($date, 'n') . "\n";
?>

The output of the above code will be:

❮ PHP Date and Time Reference