Simple Data Types

Data types are used to define fields , variables.
In C# there are various data types, but let's start with the basic ones:
int, string, double, char and bool

When defining a variable we first need to set its type and then its name For example: string CompanyName;
string – is the type of the variable
CompanyName is the variable’s name.

Notice the standard naming conventions: the name of the variable starts with lower case and the first letter of every word afterwards is an uppercase.
You can read more about the Capitalization styles and recommendations at Capitalization Styles.

We can also initialize the variable in the same line by using the equation sign:

string companyName = "my name";

Let's create data types and display their values in the message box:

Right click on the Training folder and select Add/New Item
Choose Class and name it 'BasicTypes.cs'
In the code below 5 different data types are defined and initialized
- string, int, bool, double and char are the data types
- personName, numberOfKids, isStudent, height & gender are the variables names
- personName is initialized when it is defined
- The numberOfKids received its value in the next assignment line of code numberOfKids = 3

namespace Northwind.Training
{
    class BasicTypes
    {
       public void Run()
       {
            string personName ="Noam";
            int numberOfKids;             
            numberOfKids = 3;

            bool isStudent = false;
            double height =1.77;

            char gender ='M';
       }     
    }
}

Note:
A variable which is not in used is marked with a green underline
String VS Char
A char is a single character as opposed to a string which is comprised of many characters.
String is surrounded by double quotes while char is surrounded by a single quote.
In order to use the System.Windows.Form.MessageBox class we will add it to the using section and we will use the MessageBox.Show() method to display them

using System.Windows.Forms;
namespace Northwind.Training
{
    class BasicTypes
    {
       public void Run()
       {
           string personName ="Noam";
           int numberOfKids;             
           numberOfKids = 3;

           bool isStudent = false;
           double height =1.77;

           char gender ='M';

          	MessageBox.Show("Hello "  + personName ); 
          	MessageBox.Show("You have "  + numberOfKids.ToString() + " children" ); 
       }     
    }
}

When used on strings the + operator concatenates the two string into a single string.
The ToString() method is used to convert the value to string.
Every object in .net has ToString() method that convert itself to string.
When concatenating string with number you do not have to use the ToString() method this will be done automatically by C#.
To call this class from the menu we will add a new entry in the ApplicationMDI menu
DblClick on the menu so Visual Studio will generate the code that will be executed when clicking the menu entry and call this class by calling its Run() method

private void basicTypesToolStripMenuItem_Click(object sender, EventArgs e)
{
	new Training.BasicTypes().Run();
}

before running the application remember to build it.

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