C++ offers a rich set of built-in operators to various computational tasks including arithmetic, logical, bitwise, and relational operations. A powerful feature allows these symbols to be redefined for user-defined types, enhancing readability and intuitive usage.

Standard Operator Categories

Arithmetic

• Addition (+)
• Subtraction (-)
• Multiplication (*)
• Division (/)
• Modulo (%)

Relational

• Equal (==)
• Not Equal (!=)
• Greater (>)
• Less (<)
• Greater/Eq (>=)
• Less/Eq (<=)

Logical

• AND (&&)
• OR (||)
• NOT (!)

Bitwise

• AND (&)
• OR (|)
• XOR (^)
• NOT (~)
• Shift Left (<<)
• Shift Right (>>)

Assignment

• Copy (=)
• Compound variants (e.g., +=, &=, etc.)

Other

• Dereference (*)
• Address (&)
• Access (.)
• Pointer Access (->)
• Call (())
• Subscript ([])

Extending Functionality

To modify operator behavior for custom structs or classes, developers implement special member functions or utilize friend functions.

Arithmetic Redefinition

#include <iostream>

struct Vector2D {
    float x, y;
    
    Vector2D(float a = 0.0f, float b = 0.0f) : x(a), y(b) {}

    Vector2D operator+(const Vector2D& rhs) const {
        return Vector2D(x + rhs.x, y + rhs.y);
    }
    
    void print() const {
        std::cout << "[" << x << ", " << y << "]" << std::endl;
    }
};

int main() {
    Vector2D p1(1.0f, 2.0f);
    Vector2D p2(3.0f, 4.0f);
    Vector2D result = p1 + p2;

    result.print();
    return 0;
}

Relational Redefinition

#include <iostream>

struct Vector2D {
    float x, y;
    
    Vector2D(float a = 0.0f, float b = 0.0f) : x(a), y(b) {}

    bool operator==(const Vector2D& rhs) const {
        return (x == rhs.x) && (y == rhs.y);
    }
    
    void print() const {
        std::cout << "(" << x << ", " << y << ")" << std::endl;
    }
};

int main() {
    Vector2D a(1.0f, 1.0f);
    Vector2D b(1.0f, 1.0f);

    if (a == b) {
        std::cout << "Match found." << std::endl;
    }
    return 0;
}

Stream Integration

Friends allow injection into IO streams:

#include <iostream>

struct Vector2D {
    float x, y;
    
    Vector2D(float a = 0.0f, float b = 0.0f) : x(a), y(b) {}

    friend std::ostream& operator<<(std::ostream& os, const Vector2D& v) {
        os << "(" << v.x << "," << v.y << ")";
        return os;
    }

    friend std::istream& operator>>(std::istream& is, Vector2D& v) {
        is >> v.x >> v.y;
        return is;
    }
};

int main() {
    Vector2D input;
    std::cout << "Enter values: ";
    std::cin >> input;
    std::cout << "Data: " << input << std::endl;
    return 0;
}