Dates, Times, and Formatting

Date Arithmetic

Add days to a fixed date and compare the result.

Date Arithmetic

DateArithmetic.cs 
using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        int addDays = ;
        DateTime start = new DateTime(2026, 4, 10);
        DateTime due = start.AddDays(addDays);
        bool sameMonth = start.Month == due.Month;

        string dueText = due.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture);

        Console.WriteLine($"due={dueText}");
        Console.WriteLine($"sameMonth={sameMonth}");
    }
}

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        int addDays = ;
        DateTime start = new DateTime(2026, 4, 10);
        DateTime due = start.AddDays(addDays);
        bool sameMonth = start.Month == due.Month;

        string dueText = due.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture);

        Console.WriteLine($"due={dueText}");
        Console.WriteLine($"sameMonth={sameMonth}");
    }
}

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
        int addDays = ;
        DateTime start = new DateTime(2026, 4, 10);
        DateTime due = start.AddDays(addDays);
        bool sameMonth = start.Month == due.Month;

        string dueText = due.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture);

        Console.WriteLine($"due={dueText}");
        Console.WriteLine($"sameMonth={sameMonth}");
    }
}
dates Date methods return new values, so arithmetic can be assigned and formatted.