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!");    
    }
  }
}

Example explained

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

Line 2: A blank line. C# ignores white space. However, multiple lines makes the code more readable.

Line 3: namespace is a 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.

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:

WriteLine or Write

The most common method to output something in C# is WriteLine(), but you can also use Write().

The difference is that WriteLine() prints the output on a new line each time, while Write() prints on the same line (note that you should remember to add spaces when needed, for better readability):

Console.WriteLine("Hello World!");  
Console.WriteLine("I will print on a new line.");

Console.Write("Hello World! ");
Console.Write("I will print on the same line.");  

In this tutorial, we will only use WriteLine() as it makes it easier to read the output of code.

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