Operator Overloading in C++

Operator Overloading in C++

• Operators can be overloaded to perform specific operations for user-defined classes.
• Existing operators (+, -, *, /, etc.) can have their behavior redefined for custom data types.
• Overloaded operators are defined as functions with the operator keyword followed by the symbol being overloaded.

Overloaded Operators as Functions

• Function definitions are written similar to other functions, with a header and body.
• operator+ would be used to overload the addition operator.
• The name of the function is operator, followed by + (or the corresponding arithmetic operator).
• For example, operator+ to overload the + operator for a custom class.

Example Class: Arithmetic

• A class demonstrating operator overloading for basic arithmetic operations.

class Arithmetic {
  public:
    Arithmetic(int = 1);
    Arithmetic operator+(Arithmetic);
    Arithmetic operator-(Arithmetic);
    Arithmetic operator*(Arithmetic);
    Arithmetic operator/(Arithmetic);
    Arithmetic operator%(Arithmetic);
    Arithmetic operator++();
    void printNumber();

private:
     int num;
};

• Overload operators for addition, subtraction, multiplication, division and modulo arithmetic
• The printNumber() function prints the value of num, and a constructor.

Operator Overloading Techniques

• Member functions: Operators are defined as member functions. The left-hand operand is implicitly the object on which the function is invoked. Example:

Arithmetic Arithmetic::operator+(Arithmetic b) {
    Arithmetic c;
    c.num = num + b.num;
    return c;
}

• Non-member (friend) functions: Suitable for operators where one of the operands needs to be of a different class type. Example:

Arithmetic operator-(Arithmetic a, Arithmetic b) {
     Arithmetic temp;
     temp.num = a.num - b.num;
     return temp;
}

• Friend Functions: Used to allow non-member functions access to private members operator-.
• The operators can be overloaded as either member functions or non-member friend functions.

Example Usage (int main())

• Demonstrates how overloaded operators work with objects of the Arithmetic class.

int main() {
    Arithmetic x(11), y(5), z;
    z = x + y;
    .
    .
    .
}

• Calls to overloaded plus operator, print, operator subtraction,.

Operator Overloading Limitations

• Some operators cannot be overloaded (e.g., ::, .).
• Overloading precedence of operators is not allowed.
• You cannot create new operators, just change the existing ones.