Answer.

Function overloading is the ability to create multiple functions with the same name but different arguments. This is used to improve readability and provide an intuitive interface.

Operator overloading is the ability to define how standard operators work with user-defined data types (classes or structures).

Limitations of operator overloading:

• Not all operators can be overloaded (.:, .*, ::, sizeof, ?:, etc.).
• The operator must be either a member function or a friend function.
• It is not possible to completely redefine the semantics to create a new syntax.

Example of overloading the "+" operator:

class Vector2D {
public:
    float x, y;
    Vector2D(float _x, float _y): x(_x), y(_y) {}
    Vector2D operator+(const Vector2D& rhs) const {
        return Vector2D(x + rhs.x, y + rhs.y);
    }
};

Trick question.

Is it allowed to overload the comma operator (,) in C++ and if so, for what purpose can it be used?

Answer:
Yes, the comma operator can be overloaded for user-defined classes.
However, overloading the comma operator should only be done when there is a good reason, as it can confuse the reader of the code and lead to unexpected consequences.

struct Logger {
    Logger& operator,(const std::string& msg) {
        std::cout << msg;
        return *this;
    }
};

Examples of real errors due to ignorance of the intricacies of the topic.

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In a mathematical library, the == operator was overloaded for comparing objects, but the < operator was forgotten. This led to compilation errors when trying to use STL containers that require a comparison operator, e.g., std::set, std::map.

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A developer overloaded the + operator for the Matrix class but instead of returning a new object, always modified the left operand. The result was unexpected side effects and a violation of the principle of "purity" of operations.

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When overloading a function with different types of arguments, the const qualifier was not taken into account:

void foo(SomeClass&);
void foo(const SomeClass&);

This led to ambiguity in the function call and compilation errors when passing temporary objects.