`DayOfWeek`

7 days are in each week. In C# programs we can determine if a certain date is a Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday.

The DayOfWeek property, and the DayOfWeek enum type, can be used for this purpose. These 2 types have the same name, but are different (and often used together).

Initial example

To begin, we look at a program that acquires the current DayOfWeek. You can use either DateTime.Now or DateTime.Today to get the current day.

Then You can take the DayOfWeek from the DateTime instance. DayOfWeek is a property, and also an enum type.

Next We use if or switch on a DayOfWeek. We test what day of the week was found using an if-expression.

And In the example output, the DO WORK line only appears if the program was run on a Monday.

Finally We print (with Console.WriteLine) all the values of the DayOfWeek enum for completeness.

using System;

class Program
{
    static void Main()
    {
        // Get current day of week.
        DayOfWeek today = DateTime.Today.DayOfWeek;
        Console.WriteLine("Today is {0}", today);

        // Test current day of week.
        if (today == DayOfWeek.Monday)
        {
            Console.WriteLine("DO WORK");
        }

        // Demonstrate all DayOfWeek values.
        Console.WriteLine("{0}, {1}, {2}, {3}, {4}, {5}, {6}",
            DayOfWeek.Monday,
            DayOfWeek.Tuesday,
            DayOfWeek.Wednesday,
            DayOfWeek.Thursday,
            DayOfWeek.Friday,
            DayOfWeek.Saturday,
            DayOfWeek.Sunday);
    }
}Today is Monday
DO WORK
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday

Day list

We can use DayOfWeek in collections like a list. We do not need to use the DayOfWeek property in the same program as the DayOfWeek enum.

Here We use the DayOfWeek enum to represent work days in a List. We then loop over and print the day names.

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Use a DayOfWeek list.
        List<DayOfWeek> workDays = new List<DayOfWeek>();
        workDays.Add(DayOfWeek.Monday);
        workDays.Add(DayOfWeek.Wednesday);

        // Loop over list of days.
        foreach (var day in workDays)
        {
            Console.WriteLine($"WORK DAY: {day}");
        }
    }
}WORK DAY: Monday
WORK DAY: Wednesday

A summary

The DayOfWeek enum is a convenient type for representing the day of the week as a small value. This type can be used anywhere.