Question

How to calculate the week number for a given date in C#

Answer 1

using System;

class Program
{
    static void Main(string[] args)
    {
        DateTime date = new DateTime(2025, 3, 14);
        int weekNumber = GetWeekNumber(date);

        Console.WriteLine($"Week number: {weekNumber}");
    }

    static int GetWeekNumber(DateTime date) {
        DateTime startDate = new DateTime(date.Year, 1, 1);
        int days = (int)(date - startDate).TotalDays;

        return (days + (int)startDate.DayOfWeek + 1) / 7 + 1;
    }
}



/*
run:

Week number: 11

*/

 

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