Operators

An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations.C# has rich set of built-in operators and provides the following type of operators

Common operators:

Arithmetic Operators like +,-,*,/,%

Assignment Operator =,+=,-=,*=,/=,%=

Comparison Operators like ==, !=,>, >=, <, <=

Conditional Operators like &&, ||

Ternary Operator ?:

Null Coalescing Operator ??

Example:

using System;
class Program
{
    static void Main()
    {
        int a = 21;
        int b = 10;
        int c;

        Console.WriteLine("Examples of Arithmetic operators");
        c = a + b;
        Console.WriteLine(" 1 - Value of c is {0}", c);
        c = a - b;
        Console.WriteLine(" 2 - Value of c is {0}", c);
        c = a * b;
        Console.WriteLine(" 3 - Value of c is {0}", c);
        c = a / b;
        Console.WriteLine(" 4 - Value of c is {0}", c);
        c = a % b;
        Console.WriteLine(" 5 - Value of c is {0}", c);

        Console.WriteLine("Assignment operators");
        c = a;
        Console.WriteLine(" 1 - =  Value of c = {0}", c);
        c += a;
        Console.WriteLine(" 2 - += Value of c = {0}", c);
        c -= a;
        Console.WriteLine(" 3 - -=  Value of c = {0}", c);
        c *= a;
        Console.WriteLine(" 4 - *=  Value of c = {0}", c);
        c /= a;
        Console.WriteLine(" 5 - /=  Value of c = {0}", c);
        c = 200;
        c %= a;
        Console.WriteLine(" 6 - %=  Value of c = {0}", c);

        Console.WriteLine("Comparison operators");
        if (a == b)
        {
            Console.WriteLine(" 1 - a is equal to b");
        }
        else
        {
            Console.WriteLine(" 1 - a is not equal to b");
        }

        if (a < b)
        {
            Console.WriteLine(" 2 - a is less than b");
        }
        else
        {
            Console.WriteLine(" 2 - a is not less than b");
        }

        if (a > b)
        {
            Console.WriteLine(" 3 - a is greater than b");
        }
        else
        {
            Console.WriteLine(" 3 - a is not greater than b");
        }
        if (a <= b)
        {
            Console.WriteLine(" 4 - a is either less than or equal to  b");
        }

        if (b >= a)
        {
            Console.WriteLine(" 5 - b is either greater than or equal to b");
        }
        if (a !=b )
        {
            Console.WriteLine(" 6 - a is not equal  to b");
        }

        Console.WriteLine("conditional operators");

        bool d = true;
        bool e = true;

        if (d && e)
        {
            Console.WriteLine(" 1 - Condition is true");
        }

        if (d || e)
        {
            Console.WriteLine(" 2 - Condition is true");
        }
        /* lets change the value of  a and b */
        d = false;
        e = true;

        if (d && e)
        {
            Console.WriteLine(" 3 - Condition is true");
        }
        else
        {
            Console.WriteLine(" 3 - Condition is not true");
        }

        if (!(d && e))
        {
            Console.WriteLine(" 4 - Condition is true");
        }
    }
}

Ternary Operator ?:

   The ternary operator tests a condition. It compares two values. It produces a third value that depends on the result of the comparison. This can be accomplished with if-statements or other constructs.This can be accomplished with if-statements or other constructs.

Program without ternary operator:

using System;
class Program
{
    static void Main()
    {
        int a = 10;

        bool IsA10;

        if (a == 10)
        {
            IsA10 = true;
        }
        else
        {
            IsA10 = false;
        }

        Console.WriteLine("i == 10 is {0}", IsA10);

       
        Console.ReadLine();
    }
}

Program with ternary operator:

using System;
class Program
{
    static void Main()
    {
        int a = 10;

        bool IsA10 = a == 10 ? true : false;

        Console.WriteLine("i == 10 is {0}", IsA10);

    }
}

 One common use of the ternary operator is to initialize a variable with the result of the expression. It reduces multiple if-statements and nesting.

Null Coalescing Operator ??

Before discussing about null coalescing operator first we should know about nullable types in c#

Nullable types in c#

           In C# types  are divided into 2 broad categories.  
 

Value Types  - int, float, double, structs, enums etc..

Reference Types – Interface, Class, delegates, arrays etc..

By default value types are non nullable. To make them nullable use ?

int i = 0 (i is non nullable, so "i" cannot be set to null, i = null will generate compiler error)

int? j = 0 (j is nullable int, so j=null is legal)

Nullable types bridge the differences between C# types and Database types

The null coalescing operator "??" uses two question marks. With it you can use a custom value for a null reference variable. It simplifies null tests.

Program without using NULL coalescing operator

using System;
class Program
{
    static void Main()
    {
        int AvailableTickets;
        int? TicketsOnSale = null;

        if (TicketsOnSale == null)
        {
            AvailableTickets = 0;
        }
        else
        {
            AvailableTickets = (int)TicketsOnSale;
        }

        Console.WriteLine("Available Tickets={0}", AvailableTickets);


    }
}

Program with using NULL coalescing operator

using System;
using System;
class Program
{
    static void Main()
    {
        int AvailableTickets;
        int? TicketsOnSale = null;

        //Using null coalesce operator ??
        AvailableTickets = TicketsOnSale ?? 0;

        Console.WriteLine("Available Tickets={0}", AvailableTickets);
        Console.ReadLine();

    }
}