C# Language. W3Schools lessons in English

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C# Syntax

C# Syntax

In the previous chapter, we created a C# file called Program.cs, and we used the following code to print "Hello World" to the screen:


using System;

namespace HelloWorld
  class Program
    static void Main(string[] args)
      Console.WriteLine("Hello World!");


Hello World!

Try it Yourself »

Example explained

Line 1: using System means that we can use classes from the System namespace.

Line 2: A blank line. C# ignores whitespace. However, multiple lines make the code more readable.

Line 3: namespace is used to organize your code, and it is a container for classes and other namespaces.

Line 4: The curly braces {} marks the beginning and the end of a block of code.

Line 5: class is a container for data and methods, which brings functionality to your program. Every line of code that runs in C# must be inside a class. In our example, we named the class Program.

Don't worry if you don't understand how using System, namespace and class works. Just think of it as something that (almost) always appears in your program, and that you will learn more about them in a later chapter.

Line 7: Another thing that always appear in a C# program, is the Main method. Any code inside its curly brackets {} will be executed. You don't have to understand the keywords before and after Main. You will get to know them bit by bit while reading this tutorial.

Line 9: Console is a class of the System namespace, which has a WriteLine() method that is used to output/print text. In our example it will output "Hello World!".

If you omit the using System line, you would have to write System.Console.WriteLine() to print/output text.

Note: Every C# statement ends with a semicolon ;.

Note: C# is case-sensitive: "MyClass" and "myclass" has different meaning.

Note: Unlike Java, the name of the C# file does not have to match the class name, but they often do (for better organization). When saving the file, save it using a proper name and add ".cs" to the end of the filename. To run the example above on your computer, make sure that C# is properly installed: Go to the Get Started Chapter for how to install C#. The output should be:

Hello World!

C# Exercises

Test Yourself With Exercises


Insert the missing part of the code below to output "Hello World!"

static void (string[] args)
  .("Hello World!");

An anecdote about C# and Python programmers

The C# programmer decided to take a day off and went fishing. He is sitting by the river with a fishing rod when suddenly he hears a voice from the water:

— Did you know that you can optimize your fishing strategy using machine learning algorithms?

He looks around and sees only fish swimming near the surface of the water. He hears the voice again:

— You can also automate the process of casting a fishing rod using the principles of object-oriented programming.

The C# programmer looks at the fish in surprise and asks:

— What are you talking about?

The fish answers:

— Yes, I am talking. Because I am Fish-Sharp.