C# Syntax

The structure of a C# program

Look closely at the example below. It contains all of the pieces you will see in almost every C# program you write when you are starting out.

using System;

class Program
{
    static void Main()
    {
        Console.WriteLine("Understanding C# syntax");
    }
}

• using System; imports built-in features so you can use them by short names.
• class Program is a container that holds your code.
• static void Main() is the method that runs first when the program starts.
• Console.WriteLine(...) is a statement that prints text to the screen.
• Curly braces { } mark the beginning and end of a block of code.

Statements and semicolons

A statement is a single instruction that tells the program to do something. In C#, every statement must end with a semicolon. Forgetting the semicolon is one of the most common beginner mistakes.

using System;

class Program
{
    static void Main()
    {
        Console.WriteLine("Line one");
        Console.WriteLine("Line two");
    }
}

Case sensitivity and whitespace

C# treats uppercase and lowercase letters as different. This means Console and console are not the same thing. C# ignores extra spaces and blank lines, so you are free to indent your code to make it easier to read.