F_GetWeekOfTheYear

You can use this function to obtain the week of the year represented by a specified date and time value. The function uses the ISO 8601 standard definition of a week.

• The first week of a year is defined as the first week with four or more days in that year (DIN 1355 / ISO 8601);
• A week is considered to start an a Monday and end on Sunday.
• The returned value is between 1 and 53. The first week of a year has the number 1;
• If the first calendar day of the year is a Friday, Saturday, or Sunday, then for the first three, two, or one days of the calendar year, the F_GetWeekOfTheYear returns the last week of the previous year;
• If the last calendar day of the year is a Monday, Tuesday, or Wednesday, then for the last one, two, or three days of the calendar year, F_WeekOfTheYear returns 1 (the first week of the next calendar year);

FUNCTION F_GetWeekOfTheYear : WORD

VAR_INPUT
    in : DT;
END_VAR

PROGRAM MAIN
VAR
    dtNow      : DT := DT#2008-03-17-12:00;
    weekOfYear : WORD;
END_VAR

weekOfYear := F_GetWeekOfTheYear(dtNow);