C# .NET - English

Your First Line Of C# Code

The only thing we’ll do with the code is to write some text to the screen.
But here’s the code that Visual C# prepares for you when you first create a
Console Application:

The only thing we’ll do with the code is to write some text to the screen.
But here’s the code that Visual C# prepares for you when you first create a
Console Application:

Visual C# code for a Console application 

For now, ignore the lines that start with using as we’ll get to them
later in the course. But they add references to in-built code. The namespace
line includes the name of your application. A namespace is a way to group related
code together. Again, don’t worry about the term namespace, as you’ll learn
about these later.

The thing that’s important above is the word class. All your code will
be written in classes. This one is called Program (you can call them
anything you like, as long as C# hasn’t taken the word for itself). But think
of a class as a segment of code that you give a name to.

Inside of the class called Program there is this code:

static void Main(string[ ] args)
{

}

This piece of code is something called a Method. The name of the Method
above is Main. When you run your programme, C# looks for a Method called
Main. It uses the Main Method as the starting point for your programmes. It
then executes any code between those two curly brackets. The blue words above
are all special words – keywords. You’ll learn more about them in later chapters.

But position your cursor after the first curly bracket, and then hit the enter
key on your keyboard:

The C# Main code

The cursor automatically indents for you, ready to type something. Note where
the curly brackets are, though, in the code above. You have a pair for class
Program
, and a pair for the Main method. Miss one out and you’ll get error
messages.

The single line of code we’ll write is this (but don’t write it yet):

Console.WriteLine(“Hello C Sharp!”);

First, type the letter “C”. You’ll see a popup menu. This popup menu
is called the IntelliSense menu. It tries to guess what you want, and allows
you to quickly add the item from the list. But it should look like this, after
you have typed a capital letter “C”:

Intellisense list in C# 2010

The icon to the left of the word Console on the list above means that
it is a Class. But press the Enter key on your keyboard. The word will be added
to your code:

The C# keyword Console

Now type a full stop (period) immediately after the word Console. The IntelliSense
menu appears again:

The Write Method 

You can use the arrow keys on your keyboard to move up or down the list. But
if you type Write and then the letter L of Line, IntelliSense
will automatically move down and select it for you:

The WriteLine method 

Press the Enter key to add the word WriteLine to your code:

Your C# code

Now type a left round bracket. As soon as you type the round bracket, you’ll
see this:

The C# WriteLine options 

WriteLine is another Method (A Method is just some code that does a particular
job). But the yellow box is telling you that there are 19 different versions
of this Method. You could click the small arrows to move up and down the list.
Instead, type the following:

“Hello C Sharp!”

Don’t forget the double quotes at the start and end. These tell C# that you
want text. Your code will look like this:

The text has been added to the C# code

Now type a right round bracket:

A round bracket has been added

Notice the red wiggly line at the end. This is the coding environment’s way
of telling you that you’ve missed something out.

The thing we’ve missed out is a semicolon. All complete lines of code in C#
must end with a semicolon. Miss one out and you’ll get error messages. Type
the semicolon at the end and the red wiggly line will go away. Your code should
now look like this:

Note the semicolon at the end of the line

Note all the different colours. Visual C# colour-codes the different parts
of your code. The reddish colour between double quotes means that you want text;
the green colour means it’s a Class; blue words are ones that C# reserves for
itself.

(If you want, you can change these colours. From the menu bar at the top, click
Tools > Options. Under Environment, click Fonts and Colors.)

Time now to Build and Run your code!

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