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:
Program.cs
using System;
namespace HelloWorld
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
}
}
}
Result:
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.
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!
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):
Example
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.");
Result:
Hello World!
I will print on a new line.
Hello World! 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.