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Operator Overloading In C#

What is operator?

Operators are the symbols, which are used to perform an operation between the operands. As,
 
a + b 
Operands : a and b
Operator : +
 
Type of operators:
 
Operators are of two types, which are:
 
Unary Operators : ++, --, -
 
Binary Operators : +, -, *, /, >, <, =, == etc.
 
Why operator overloading is required? 
 
Usually, the operators work with the pre-defind type like int, float, string etc. If you want to perform an operation on the user defined type (object), it is required to re-define the operators (overload) to perform the operation.  
  1. Number n1=new Number(10,20);  
  2. Number n2=new Number(5,10);  
  3. Number n3=n1+n2;   
n1 and n2 are two user defined types (object) and + operator is required to perform an addition between the two objects. This is only possible with the operator overloading.
 
Example:
 
Create a class to define a user defined type (object). 
  1.  class Numbers  
  2.  {  
  3.         public int num1, num2;  
  4.         public Numbers()  
  5.         {  
  6.             num1 = 0;  
  7.             num2 = 0;  
  8.         }  
  9.         public Numbers(int a,int b)  
  10.         {  
  11.             num1 = a;  
  12.             num2 = b;  
  13.         }  
  14.         public void PrintNumbers()  
  15.         {  
  16.             Console.WriteLine("Num1 :"+num1);  
  17.             Console.WriteLine("Num2 :" + num2);  
  18.         }  
  19. }    
Write the code to redefine the operators (overload) to perform a user defined operation.
 
Operator overloading : + 
  1. public static Numbers operator +(Numbers ob1, Numbers ob2)  
  2. {  
  3.             Numbers ob3 = new Numbers();  
  4.             ob3.num1 = ob1.num1 + ob2.num1;  
  5.             ob3.num2 = ob1.num2 + ob2.num2;  
  6.             return ob3;  
  7. }   
Operator overloading : ++ 
  1. public static Numbers operator ++(Numbers ob1)  
  2. {  
  3.             Numbers ob2 = new Numbers ();  
  4.             ob2.num1 = ob1.num1 + 1;  
  5.             ob2.num2 = ob1.num2 + 1;  
  6.             return ob2;  
  7. }    
Operator overloading : > 
  1. public static bool operator >(Numbers ob1, Numbers ob2)  
  2.         {  
  3.             if (ob1.num1 > ob2.num1 && ob1.num2 > ob2.num2)  
  4.             {  
  5.                 return true;  
  6.             }  
  7.             else  
  8.             {  
  9.                 return false;  
  10.             }  
  11. }   
Operator overloading : <
  1. public static bool operator <(Numbers ob1, Numbers ob2)  
  2. {  
  3.             if (ob1.num1 < ob2.num1 && ob1.num2 < ob2.num2)  
  4.             {  
  5.                 return true;  
  6.             }  
  7.             else  
  8.             {  
  9.                 return false;  
  10.             }  
  11. }   
Write the statement in Main method to test the Application.
 
Statement 1 - To test + operator overloading.
  1. Numbers n1 = new Numbers();  
  2. Numbers n2 = new Numbers(10,20);  
  3. Numbers n3 = new Numbers(20,30);  
  4. n1 = n2 + n3;  
  5. n1.PrintNumbers();   
Statement 2 - To test ++ operator overloading.
  1. Numbers n1 = new Numbers();  
  2. Numbers n2 = new Numbers(10,20);  
  3. //Pre increment  
  4. n1 = ++n2;  
  5. n1.PrintNumbers();  
  6. n2.PrintNumbers();   
  7.   
  8. //Post increment  
  9. n1 = n2++;  
  10. n1.PrintNumbers();  
  11. n2.PrintNumbers();    
Statement 3 - To test >operator overloading.
  1. Numbers n1 = new Numbers(10,20);  
  2. Numbers n2 = new Numbers(20,30);   
  3. if (n1 > n2)  
  4. {  
  5.     Console.WriteLine("True");  
  6. }  
  7. else  
  8. {  
  9.     Console.WriteLine("False");  
  10. }  
Statement 4 - To test < operator overloading. 
  1. Numbers n1 = new Numbers(10,20);  
  2. Numbers n2 = new Numbers(20,30);   
  3. if (n1 < n2)  
  4. {  
  5.     Console.WriteLine("True");  
  6. }  
  7. else  
  8. {  
  9.     Console.WriteLine("False");  
  10. }   
Note

Some of the operators are not overloaded. As- =, ?:,->, sizeof, new etc.The comparison operators must be overloaded in the pairs.
 
That's all. Thank you. If any suggestion or clarification is required, kindly revert back with the comments.