C sharp - Overloading Binary Operators in C#

Operator overloading allows you to redefine the behavior of binary operators (like +, -, *, etc.) for user-defined types (typically classes and structs).

Basic Syntax

To overload a binary operator, define a public static method using the operator keyword.

public static ReturnType operator <operator>(Type lhs, Type rhs)

• ReturnType: The type the operation returns.

• lhs and rhs: Left-hand and right-hand side operands.

• <operator>: The operator you want to overload (e.g., +, -, *, /, ==, etc.).

Example: Overloading + Operator

Let's create a Point class that adds two points:

class Program
{
    static void Main()
    {
        Point p1 = new Point(2, 3);
        Point p2 = new Point(4, 5);
        Point p3 = p1 + p2;
        Console.WriteLine(p3);  // Output: (6, 8)
    }
}

Other Common Binary Operators You Can Overload

Note: When you overload ==, you must also overload !=, and usually override Equals() and GetHashCode() for consistency.

Rules and Restrictions

• Only classes or structs can overload operators.

• You cannot overload operators for built-in types (like int, double).

• You must declare operator methods as public static.

• You cannot overload logical operators like && and || directly unless you also overload & and |.