❮ Csharp Queue Csharp Collection ❯

C# Program Structure

Before we delve into the fundamental building blocks of the C# programming language, let's first look at the minimal structure of a C# program to serve as a reference for the upcoming chapters.

C# Hello World Example

A C# program generally includes the following parts:

Namespace declaration
A class
Class methods
Class attributes
A Main method
Statements & Expressions
Comments

The file extension for C# files is .cs.

Below is a test.cs file that contains simple code to print "Hello World":

test.cs File Code:

using System;
namespace HelloWorldApplication
{
   class HelloWorld
   {
      static void Main(string[] args)
      {
         /* My first C# program */
         Console.WriteLine("Hello World");
         Console.ReadKey();
      }
   }
}

When the above code is compiled and executed, it produces the following result:

Hello World

Let's examine the various parts of the program:

The first line using System; - The using keyword is used to include the System namespace in the program. A program typically has multiple using statements.
The next line is a namespace declaration. A namespace contains a set of classes. The HelloWorldApplication namespace contains the class HelloWorld.
The next line is a class declaration. The class HelloWorld contains the data and method definitions used by the program. A class usually contains multiple methods. Methods define the behavior of the class. Here, the HelloWorld class has only one Main method.
The next line defines the Main method, which is the entry point for all C# programs. The Main method specifies the actions the class will perform when executed.
The line /.../ will be ignored by the compiler and it adds additional comments to the program.
The Main method specifies its behavior with the statement Console.WriteLine("Hello World");.

WriteLine is a method of the Console class defined in the System namespace. This statement displays the message "Hello World" on the screen.

The last line Console.ReadKey(); is for VS.NET users. This makes the program wait for a key press, preventing the screen from quickly running and closing when launched from Visual Studio .NET.

A few important points to note:

C# is case-sensitive.
All statements and expressions must end with a semicolon (;).
Program execution starts from the Main method.
Unlike Java, the file name can be different from the class name.

Compiling & Executing C# Program

If you are using Visual Studio.Net to compile and execute a C# program, follow these steps:

Start Visual Studio.
On the menu bar, choose File -> New -> Project.
Select Visual C# from the templates, then choose Windows.
Choose Console Application.
Name your project and click OK.
The new project will appear in the Solution Explorer.
Write the code in the code editor.
Click the Run button or press F5 to run the program. A command prompt window will appear, displaying "Hello World".

You can also compile a C# program using the command line instead of Visual Studio IDE:

Open a text editor and add the code mentioned above.
Save the file as helloworld.cs.
Open the command prompt tool and navigate to the directory where the file is saved.
Type csc helloworld.cs and press enter to compile the code.
If there are no errors, the command prompt will move to the next line and generate the helloworld.exe executable file.
Next, type helloworld to execute the program.
You will see "Hello World" printed on the screen.

❮ Csharp Queue Csharp Collection ❯