Types

C# is a strongly typed language.

Every variable must be defined by a type.

The following is a list of common types used in C#:

string
int
long
decimal
bool
DateTime

Strings

The string type is used for text.

Write the following code in the Main method :

using System;

namespace LearnCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            string name = "Anil";
            Console.WriteLine($"Hello {name}");
        }
    }
}

Run the application in the Console Window

Output in Console Window

Hello Anil

The variable, name is of type string.

The value of the name variable is set to ‘Anil’.

Integers

Integers (int) are used to represent whole numbers (e.g. 3, 5, etc.). The range for the int type is : -2,147,483,648 to 2,147,483,647.

The long type has a greater range : -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

Write the following code :

using System;

namespace LearnCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            int x = 1;
            int y = 3;
            int sum = x + y;
            Console.WriteLine($"Sum : {sum}");
        }
    }
}

Run the application in the Console Window

Output in Console Window

Sum : 4

Decimal

The type Decimal is used to represent decimal numbers (eg: 3.14).

Write the following code :

using System;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            Decimal pi = 3.14M;
            Console.WriteLine($"The value of pi is {pi}");
        }
    }
}

Run the application in the Console Window

Output in Console Window

The value of pi is 3.14

‘M’ is used to specify that the number is a decimal.

Bool

The type bool is used to represent true or false (Boolean) values.

Write the following code :

using System;

namespace LearnCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            bool b = true;
            Console.WriteLine($"{b}");
        }
    }
}

Run the application in the Console Window

Output in Console Window

True

DateTime

The type DateTime is used to represent Date and Time.

Write the following code :

using System;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            DateTime now = DateTime.Now;
            Console.WriteLine($"The current date and time is {now}");
        }
    }
}

Run the application in the Console Window

Output in Console Window

The current date and time is 1/27/2020 4:27:54 PM

Arrays

You can store multiple variables of the same type in an array data structure.

You declare an array by specifying the type of its elements.

Note the index starts from 0.

using System;

namespace LearnCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] numbers = { 3, 0, 4, 8, 2 };
            int a = numbers[3];
            Console.WriteLine($"The fourth number in the array is : {a}");
        }
    }
}