Question

Assume a class named Yen exists. Write the header for a member function that overloads the \(<\) operator for that class.

Short answer

Answer: The header for the member function that overloads the "<" operator for the Yen class is: ```cpp class Yen { // Class member variables and functions here friend bool operator<(const Yen& lhs, const Yen& rhs); }; bool operator<(const Yen& lhs, const Yen& rhs); ```

Step-by-step solution

Declare a friend function within the Yen class.

To give the "<" operator function access to the private and protected member data, declare it as a friend function within the "Yen" class. ```cpp class Yen { // Class member variables and functions here friend bool operator<(const Yen& lhs, const Yen& rhs); }; ```

Write the header for the overloaded "

Now, define the header for the overloaded "<" operator function outside the class. Make sure to add the "friend" keyword in front of the function declaration to indicate that it's a friend function of the Yen class. ```cpp bool operator<(const Yen& lhs, const Yen& rhs); ``` The header for the member function that overloads the "<" operator for the Yen class is: ```cpp class Yen { // Class member variables and functions here friend bool operator<(const Yen& lhs, const Yen& rhs); }; bool operator<(const Yen& lhs, const Yen& rhs); ```

Key concepts

C++ Operator Overloading

In C++, operator overloading is a powerful feature that allows developers to redefine how existing operators work with user-defined types. Overloading operators makes it easier to perform operations on objects just like you would with fundamental types.

For example, the '<' operator, which is traditionally used to compare numerals, can be redefined to compare two objects of class Yen. When you overload an operator in C++, you create a function that specifies what should happen when that operator is used with one or more objects of your class.

Let's say you're dealing with a financial application where comparing amounts of Yen is frequent. Instead of writing out a long method like object1.isLessThan(object2), with operator overloading you could simply write object1 < object2 after defining this comparison logic within your class.

• The function must be marked with the keyword operator followed by the operator symbol.
• The operator function can be a member function or a global function. For binary operators like '<', it usually takes two parameters representing the left and right operands.
• If the operator function is a member function, it only needs one explicit parameter, as the left operand is represented by the implicit this pointer.

Friend Functions in C++

Friend functions in C++ provide a way to give functions or another class access to private and protected members of a class.

In the context of operator overloading, friend functions are especially useful when creating binary operators like '+' or '<'. Unlike member functions, friend functions do not belong to a class but still require access to its internal members.

• A friend function is declared in the class body prefixed with the keyword friend.
• It is not a member function, so it doesn't have this pointer.
• When an operator is implemented as a friend function, it can access the private and protected data of the class it's friending.

To incorporate a friend function into the Yen class as shown in the solution, it allows us to write a clean and readable syntax for comparing Yen objects, while still maintaining encapsulation of private data.

C++ Class Member

A class in C++ is a blueprint for creating objects. A class member represents a data point or a function that’s tied to the class. Class members include data members (variables) and member functions (methods).

Data members define the properties of the objects, while member functions define the actions that can be performed on them.

Types of Class Members

• Member Variables: Holds the data each object keeps track of.
• Member Functions: Defines behaviors or actions that can be performed on or by the object.
• Static Members: Belongs to the class itself, not to any particular object instantiated from the class.

Remember, every object of a class will have its own copy of all the non-static data members, but they all share a single copy of the static members.

C++ Private and Protected Members

In C++, access specifiers define how class members are accessed outside the class. Private and protected members are two types of access restrictions that a class can impose.

Private members of a class are accessible only within the class itself or by friends of the class. They are not available to the outside world, providing a strict level of encapsulation that protects the integrity of the object's data.

Protected members sit between private and public access specifiers. They are similar to private members but with an added level of accessibility such that classes derived (or inherited) from the base class can also access them.

Key Points:

• Private members cannot be accessed directly from outside the class; they can only be accessed through member functions or friend functions.
• Protected members allow a base class to share its characteristics with derived classes while preventing outside access.
• Defining a member as private or protected is a crucial part of object-oriented design, ensuring data hiding and encapsulation.