CSharp Basics ConsoleWriteLine DateTime

C# Basics: Console.WriteLine and DateTime

This lesson introduces two fundamental building blocks of C# console programs:

• Console.WriteLine for output
• DateTime for working with dates and times

Related wiki pages:

• General C# overview: CSharpBible.md
• Console helper libraries: CSharpBible-Library-ConsoleLib.md

Official documentation:

• Console: https://learn.microsoft.com/dotnet/api/system.console
• DateTime: https://learn.microsoft.com/dotnet/api/system.datetime

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1. A simple example

using System;

public class Example
{
    public static void Main(string[] args)
    {
        // Create a DateTime object for a specific date
        DateTime now = new DateTime(2024, 12, 6);  // 6 December 2024

        // Print the date
        Console.WriteLine("Today is: {0}", now);
    }
}

Explanation:

1. using System; – Imports the System namespace with basic types like Console and DateTime.
2. public class Example – Defines a class named Example.
3. public static void Main(string[] args) – Entry point of the program.
4. new DateTime(2024, 12, 6) – Constructs a specific date.
5. Console.WriteLine("Today is: {0}", now); – Writes formatted text to the console.

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2. Running the program (SDK-style)

With the .NET SDK you typically use a project instead of calling csc directly:

1. Create a new console app:
   • dotnet new console -n DateTimeSample
2. Replace the contents of Program.cs with the example above.
3. Run:
   • dotnet run

You should see something like:

Today is: 06.12.2024 00:00:00

The exact format depends on your system culture.

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3. Formatting DateTime

You can format dates using ToString with format strings:

DateTime now = DateTime.Now;

Console.WriteLine(now.ToString("yyyy-MM-dd"));      // 2024-12-06
Console.WriteLine(now.ToString("dd.MM.yyyy"));      // 06.12.2024
Console.WriteLine(now.ToString("O"));               // ISO 8601

See the DateTime docs for a full list of standard and custom format strings.

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4. Next steps

• Use Console.ReadLine to read user input and print it back.
• Combine Console I/O with control structures shown in other lessons in this wiki (see CSharpBible.md for navigation).
• Explore helper utilities in CSharpBible-Library-ConsoleLib.md if available.