C#: Find the first day of a week against a given date

Last update on December 20 2024 12:40:08 (UTC/GMT +8 hours)

Write a program in C# Sharp to find the first day of a week against a given date.

Sample Solution:-

C# Sharp Code:

using System; // Importing the System namespace

class dttimeex52 // Declaring a class named dttimeex52
{
    static void Main() // Declaring the Main method
    {
        int yr, mn, dt; // Declaring variables for year, month, and day

        Console.Write("\n\n Find the first day of a week against a given date :\n"); // Displaying a message in the console
        Console.Write("--------------------------------------------------------\n"); // Displaying a separator line

        // Input prompts for day, month, and year
        Console.Write(" Input the Day : ");
        dt = Convert.ToInt32(Console.ReadLine());
        Console.Write(" Input the Month : ");
        mn = Convert.ToInt32(Console.ReadLine());
        Console.Write(" Input the Year : ");
        yr = Convert.ToInt32(Console.ReadLine());

        DateTime d = new DateTime(yr, mn, dt); // Creating a DateTime object with the provided year, month, and day
        Console.WriteLine(" The formatted Date is : {0}", d.ToString("dd/MM/yyyy")); // Displaying the formatted input date
        Console.WriteLine(" The first day of the week for the above date is : {0}\n", FirstDayOfWeek(d).ToString("dd/MM/yyyy")); // Displaying the first day of the week for the input date
    }

    // Method to find the first day of the week given a specific date
    public static DateTime FirstDayOfWeek(DateTime dt)
    {
        var culture = System.Threading.Thread.CurrentThread.CurrentCulture; // Getting current culture information
        var diff = dt.DayOfWeek - culture.DateTimeFormat.FirstDayOfWeek; // Calculating the difference between the input date's day of the week and the first day of the week in the culture

        if (diff < 0)
            diff += 7; // If the difference is negative, add 7 days to get the correct first day of the week

        return dt.AddDays(-diff).Date; // Returning the date adjusted to the first day of the week
    }
}

Sample Output:

Find the first day of a week against a given date :                                                          
--------------------------------------------------------                                                      
 Input the Day : 12                                                                                           
 Input the Month : 06                                                                                          
 Input the Year : 2017                                                                                        
 The formatted Date is : 12/06/2017                                                                           
 The first day of the week for the above date is : 11/06/2017

Flowchart:

C# Sharp Code Editor:

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