How to write the first program in C#?

Writing your first program in C# is the foundation of learning this powerful programming language. A C# program consists of several key components that work together to produce output. Let's explore the structure and elements of a basic C# program.

Syntax

Following is the basic structure of a C# program −

using System;

namespace NamespaceName {
   class ClassName {
      static void Main(string[] args) {
         // Program logic here
         Console.WriteLine("Your message");
      }
   }
}

Example

using System;

namespace MyHelloWorldApplication {
   class MyDemoClass {
      static void Main(string[] args) {
         // display text
         Console.WriteLine("Hello World");

         // display another text
         Console.WriteLine("Welcome!");
      }
   }
}

The output of the above code is −

Hello World
Welcome!

Understanding the Program Structure

Let us examine each component of the program −

• using System; − The using keyword imports the System namespace, which contains fundamental classes like Console.

• namespace declaration − A namespace is a container that groups related classes. The MyHelloWorldApplication namespace contains the class MyDemoClass.

• class declaration − The class MyDemoClass contains the data and method definitions. Classes are the building blocks of C# programs.

• Main method − The Main method is the entry point for all C# programs. When you run the program, execution begins here.

• Console.WriteLine() − This method from the Console class displays text on the screen. Each call prints the specified message followed by a new line.

Using Multiple Output Statements

Example

using System;

namespace MultipleOutputs {
   class Program {
      static void Main(string[] args) {
         Console.WriteLine("Learning C# Programming");
         Console.WriteLine("Program Output:");
         Console.WriteLine("Line 1: Hello");
         Console.WriteLine("Line 2: World");
         Console.WriteLine("Line 3: Welcome to C#!");
      }
   }
}

The output of the above code is −

Learning C# Programming
Program Output:
Line 1: Hello
Line 2: World
Line 3: Welcome to C#!

Key Points

• Every C# program must have a Main method as the entry point.

• C# is case-sensitive − Main is different from main.

• Each statement ends with a semicolon (;).

• Curly braces {} define code blocks for namespaces, classes, and methods.

• Comments start with // for single-line comments.

Conclusion

Your first C# program demonstrates the essential structure: namespace, class, and Main method. The Console.WriteLine() method provides a simple way to display output. Understanding these fundamental components prepares you for writing more complex C# applications.