WeekNumber (Function)

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Default characteristics of the weeks

Characteristics of the weeks according to the ISO 8601 standard

Related examples

See also

WeekNumber (Function)

In french: NuméroDeSemaine

Returns the number of the week corresponding to the specified date.

Versions 15 and later

This function is now available for Android applications.

New in version 15

This function is now available for Android applications.

Versions 16 and later

This function is now available for Windows Phone applications.

New in version 16

This function is now available for Windows Phone applications.

Versions 17 and later

This function is now available for iPhone/iPad applications.

New in version 17

This function is now available for iPhone/iPad applications.

Versions 18 and later

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

New in version 18

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

This function is now available in Android Widget mode.

This function is now available in Windows Store apps mode.

Versions 21 and later

This function is now available in Universal Windows 10 App mode.

New in version 21

This function is now available in Universal Windows 10 App mode.

Example

WeekNumber("20010818") // Returns 33
WeekNumber("20010210") // Returns 6

// Special cases for weeks 53 and 0
WeekNumber("20081223") // Returns 52: Tuesday December 23 2008
WeekNumber("20081229") // Returns 53: Monday December 29 2008
WeekNumber("20100101") // Returns 0: Friday January 1 2010
WeekNumber("20100104") // Returns 1: Monday January 4 2010

Versions 17 and later

WeekNumber("20010818", iso8601) // Returns 33
WeekNumber("20010210", iso8601) // Returns 6

// Special case: weeks 53 and 1
WeekNumber("20081223", iso8601) // Returns 52: Tuesday December 23 2008
WeekNumber("20081229", iso8601) // Returns 1: Monday December 29 2008
WeekNumber("20100101", iso8601) // Returns 53: Friday January 1 2010
WeekNumber("20100104", iso8601) // Returns 1: Monday January 4 2010

New in version 17

Syntax

<Result> = WeekNumber(<Date> [, <Format>])

<Result>: Integer

Number of the week (between 0 and 53) corresponding to the specified date.

<Date>: Character string (with quotes), Date or DateTime variable

Date to use. This date can correspond to:
a character string in YYYYMMDD format (YYYY corresponds to the year, MM to the month and DD to the day).
Versions 24 and later
a character string in YYYYMMDDHHMMSSCC format (YYYY corresponds to year, MM to month, DD to day, HH to hour, MM to minutes, SS to seconds and CC to hundredths of a second (use CCC for milliseconds). In this case, only the date is taken into account.
New in version 24
a character string in YYYYMMDDHHMMSSCC format (YYYY corresponds to year, MM to month, DD to day, HH to hour, MM to minutes, SS to seconds and CC to hundredths of a second (use CCC for milliseconds). In this case, only the date is taken into account.
a character string in YYYYMMDDHHMMSSCC format (YYYY corresponds to year, MM to month, DD to day, HH to hour, MM to minutes, SS to seconds and CC to hundredths of a second (use CCC for milliseconds). In this case, only the date is taken into account.
a Date variable.
Versions 24 and later
a DateTime variable. In this case, only the date is taken into account.
New in version 24
a DateTime variable. In this case, only the date is taken into account.
a DateTime variable. In this case, only the date is taken into account.

<Format>: Optional Integer constant

Versions 17 and later
Format used to calculate the week number.
Versions 17 and later
iso8601
New in version 17
iso8601
iso8601 The returned week number complies with the ISO 8601 standard.
<Format> parameter not specified The returned week number corresponds to the default calculation mode.

This parameter is not available.
New in version 17
Format used to calculate the week number.
Versions 17 and later
iso8601
New in version 17
iso8601
iso8601 The returned week number complies with the ISO 8601 standard.
<Format> parameter not specified The returned week number corresponds to the default calculation mode.

This parameter is not available.
Format used to calculate the week number.
Versions 17 and later
iso8601
New in version 17
iso8601
iso8601 The returned week number complies with the ISO 8601 standard.
<Format> parameter not specified The returned week number corresponds to the default calculation mode.

This parameter is not available.

Remarks

Default characteristics of the weeks

A weeks starts on a Monday and ends on a Sunday.

For the first days of the year:

If the first day of the year is a Friday, Saturday or Sunday, the week number will be 0. The week #1 will correspond to the first Monday of the year.
If the first day of the year is a Monday, Tuesday, Wednesday or Thursday, the week number will be 1.
The days found between the Sunday of the 52nd week and January 1st are part of week 53.

You cannot calculate the week number for a date before October 14, 1582.

Versions 17 and later

Characteristics of the weeks according to the ISO 8601 standard

A weeks starts on a Monday and ends on a Sunday.

For the first days of the year:

The week #1 is the week that contains the first thursday of the year.
The week #1 is the first week that contains most of its days (at least 4 days) in the year. It systematically contains the 4th of January. If systematically contains the first working day of the year, considering that the 1st of January, the Saturdays and the Sundays are non-working days. It is the one whose Monday is nearest to the New Year's Day. It starts between the 29th of December and the 4th of January.
The last week of the year (52 or 53) is the week that contains the last Thursday of the year. It is the last one to have most of its days (at least 4) in the year and it systematically contains the 28th of December. It is the one whose Sunday is nearest to the 31st of December. It ends between the 28th of December and the 3rd of January.
There is no week zero (the week #1 of a year immediately follows the last week of the previous year).
The last days of week #1 can eventually be included at the end of December of the previous year. Similarly, the firs days of the last week (52 or 53) of a year can be included at the beginning of the next year. A year always contains 52 or 53 weeks.

You cannot calculate the week number for a date before October 14, 1582.

New in version 17

Characteristics of the weeks according to the ISO 8601 standard

A weeks starts on a Monday and ends on a Sunday.

For the first days of the year:

The week #1 is the week that contains the first thursday of the year.
The week #1 is the first week that contains most of its days (at least 4 days) in the year. It systematically contains the 4th of January. If systematically contains the first working day of the year, considering that the 1st of January, the Saturdays and the Sundays are non-working days. It is the one whose Monday is nearest to the New Year's Day. It starts between the 29th of December and the 4th of January.
The last week of the year (52 or 53) is the week that contains the last Thursday of the year. It is the last one to have most of its days (at least 4) in the year and it systematically contains the 28th of December. It is the one whose Sunday is nearest to the 31st of December. It ends between the 28th of December and the 3rd of January.
There is no week zero (the week #1 of a year immediately follows the last week of the previous year).
The last days of week #1 can eventually be included at the end of December of the previous year. Similarly, the firs days of the last week (52 or 53) of a year can be included at the beginning of the next year. A year always contains 52 or 53 weeks.

You cannot calculate the week number for a date before October 14, 1582.

Characteristics of the weeks according to the ISO 8601 standard

A weeks starts on a Monday and ends on a Sunday.

For the first days of the year:

The week #1 is the week that contains the first thursday of the year.
The week #1 is the first week that contains most of its days (at least 4 days) in the year. It systematically contains the 4th of January. If systematically contains the first working day of the year, considering that the 1st of January, the Saturdays and the Sundays are non-working days. It is the one whose Monday is nearest to the New Year's Day. It starts between the 29th of December and the 4th of January.
The last week of the year (52 or 53) is the week that contains the last Thursday of the year. It is the last one to have most of its days (at least 4) in the year and it systematically contains the 28th of December. It is the one whose Sunday is nearest to the 31st of December. It ends between the 28th of December and the 3rd of January.
There is no week zero (the week #1 of a year immediately follows the last week of the previous year).
The last days of week #1 can eventually be included at the end of December of the previous year. Similarly, the firs days of the last week (52 or 53) of a year can be included at the beginning of the next year. A year always contains 52 or 53 weeks.

You cannot calculate the week number for a date before October 14, 1582.

Related Examples:

Unit examples (WINDEV): Management of dates

[ + ] Using the Date type of WLanguage and the functions for handling dates.

Component : wd250std.dll