Here is the general syntax used when declaring a variable in C#:

[Type Name] [Variable Name] = [Value];

Let’s take a look at an example of creating a variable. First, we’ll delare a string variable called firstName, and assign a value:

 string firstName = "Bob"; 

You can declare variables without initialization, meaning that you can create them without initially assigning a value:

 string firstName; 

After the variable has been created, you can later assign a value, as needed:

 firstName = "Bob"; 

So far, all of these examples have shown creating variables of type string. There are many other built-in types that are commonly used, for example:

string firstName = "Joe";
string lastName = "Shmoe";
char middleInitial = "A";
int age = 42;

In the above example, we’ve created variables using built-in types. .NET Framework built-in types are the types you will generally use the most when declaring variables.

Built-in Types

In C#, built-in types are aliases for types defined in the .NET Framework System namespace. The table below shows the built-in types, along with their corresponding .NET Framework type:

The C# type keywords and aliases are interchangeable. Consider the following example:

 System.String lastName = "Jones"; string firstName = "Bob"; 

In the above example, the lastName and firstName variables are declared using the .NET Framework type System.String and it’s alias, string.

Custom Types

There may be times when you need to create your own type, based on a custom class. I’ll cover classes in detail in a future post, but for now let’s look at how you would create an instance of a custom type:

 Person myPerson = new Person(); 

In this example, we have declared an object of type Person. The New keyword is used to create a new instance of an object, based on the Person type.

That is all for now…In the next post, we’ll continue working through the basics of C#.

The Console class is a static class, meaning that you do not need to declare an instance of the class in order to use it’s methods. Let’s take a look at the most common Console class methods that you’ll be using when learning C#:

• Console.Write
• Console.WriteLine
• Console.ReadLine

The Write and WriteLine Methods

You’ll use the Write and WriteLine methods to display text in the command window. You’re probably wondering what the difference is between these two methods. Calling the WriteLine method prints the text on the screen, and then goes to a new line:

Console.WriteLine("Hello")
Console.WriteLine("World")

Running the above code would give you the following output:

Hello
World

Calling the Write method prints the text, without returning a new line:

Console.Write("Hello")
Console.Write("World")

Running the above code would give you the following output:

HelloWorld

The ReadLine Method

Calling the ReadLine method will pause the console, and wait for the user to provide input and the hit the enter key. You can use this method to request input from a user:

Console.WriteLine("Please enter your first name");
string firstname = Console.ReadLine();

The above code will wait for the user to type their name into the command prompt. When they hit enter, the text will be stored in the firstname string.

Formatting Strings

Building on our previous example, we can write the users name back to the console when they enter it into the program:

Console.WriteLine("Please enter your first name");
string firstname = Console.ReadLine();
Console.WriteLine("Hello, your name is {0}", firstname);

In our last call to WriteLine we are using what is called a formatted string. The {0} inside the double quotes is a place holder for our firstname variable. We could can do this for multiple strings, separated by a comma:

string firstname = "John";
string lastname = "Doe";
Console.WriteLine("Hello, your first name is {0} and your last name is {1}", firstname, lastname);

You can see in the above example that the place holders are numbered, starting at zero, and are enclosed in curly braces. The two parameters are then inserted in to the string. The firstname variable is inserted into the {0} position and the lastname variable is inserted in to the {1} position in the string.

You’ll be working with the Console class quite a bit as you go through various tutorials and books on C#. Hopefully this will make things a little more clear going forward.

1. Start Visual Studio.
2. Go to File menu > New, and then click Project.
3. In the new project screen, under Visual C#, select Windows.
4. In the Templates pane, select Console Application.
5. Type a name for your project. (I used “HelloWorld”)
6. Click OK.

At this point, you should be looking at the program.cs source code, and it should look something like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
        }
    }
}

What we want to do is add code to the Main method, that writes a message to the console that says “Hello World”. Modify the main method so it looks like this:

        static void Main(string[] args)
        {
            Console.WriteLine("Hello World");
            Console.ReadKey();
        }

Press F5 to run the project. You should get a black command prompt that displays the text “Hello World”.

Console.WriteLine is the method that writes the text to the console. We use the Console.ReadKey method to have our application pause, waiting for input. If we did not do this the console application would close immediately after running the project.

Taking it a step further

Now that we’ve got a working C# application, let’s make it a little more interactive. Modify your Main method to use the following code:

        static void Main(string[] args)
        {
            string name;
            Console.WriteLine("Please enter your name:");
            name = Console.ReadLine();

            Console.WriteLine("Hello {0}, Welcome to C#!", name);
            Console.ReadKey();
        }

When you run the project, you’ll get prompted to enter your name. When you enter your name, a message will be displayed on the screen that says hello to you. For example, if I enter John Doe as my name, the application displays “Hello John Doe, Welcome to C#!”.

Let me explain what is going on in this example.

• First, we declare a string variable called “name” (I’ll cover variables further in a later post).
• Next, we again use Console.WriteLine to display a message, asking the user for their name.
• We then assign the Console.ReadLine method to the name variable. This allows us to prompt the user for their name, and store the string in the name variable.
• Finally, we write a message to the console saying hello to the user name that was entered into our application. You may notice the syntax in this line is a little different. This is because we are using string formatting, I’ll cover strings in detail in a future post.

Congratulations, you’ve just written your first working C# program. In the coming posts I’ll be covering all of the basics to get you up and running and programming in C#.

• Types & Variables
• Arrays
• Strings and Characters
• Expressions and Operators
• Statements
• Namespaces
• Classes and Structs
• Inheritance
• Properties
• Indexers
• Delegates
• Events
• Generics
• LINQ
• Lambda Expressions
• Enumeration and Iterators
• Nullable Types
• Extention Methods

…and much more!

I hope, over time, you find this blog as a valuable resource in learning C#!