Question

Assume a class named Collection exists. Write the header for a member function that overloads the \(|]\) operator for that class.

Short answer

Based on the given step by step solution, the header for the overloaded [] operator for the given "Collection" class is: ```cpp int& operator[](int index); ```

Step-by-step solution

Class Definition

First, we need to define the class named "Collection". The class definition should look like this: ```cpp class Collection { // Class members go here }; ```

Add a Member Function for Operator Overloading

Inside the Collection class, we will add the member function for overloading the [] operator. We'll assume the class is handling a collection of integers. Thus, the function should return an int reference. The function should take an index as an argument. ```cpp class Collection { public: int& operator[](int index); // Overloads the [] operator // Other class members go here }; ``` The header for the overloaded [] operator is now complete. Note that if the Collection class had a different data type, the return type of the 'operator[]' function and its implementation should be modified accordingly.

Key concepts

C++ Classes

In the world of C++, a class represents a blueprint for an object. Think of a class as a template that defines the form and behavior of objects created from it. Whether it pertains to a 'Collection', as in the exercise, or any other entity, classes are foundational to C++'s object-oriented capabilities.

Within a class, you can define attributes (also known as data members) which are the properties that an object of this class will have, and methods (also known as member functions), which are the functions that operate on these attributes. Classes encapsulate data for the object and methods to manipulate that data, maintaining a tight control over how other parts of the program interact with it.

When a class is defined, no memory is allocated until an object is created (instantiated). Each object called an instance of the class, holds its own copy of attributes and shares the common methods defined.

Overloading [] Operator

The beauty of C++ lies in its ability to let programmers define the behavior of operators for their own classes, a feature known as operator overloading. In the context of our exercise, overloading the [] operator allows a class to mimic the behavior of arrays or similar data structures.

When overloading an operator like the [], a member function is created with a special name: operator[]. This allows object instances to use square brackets, just like an array, to access elements. The [] operator must be a member function, and its typical use case is to grant access to elements within a collection, as the name implies.

In cases where the operator needs to modify the accessed element, it returns a reference. This is exactly what is done in the exercise, where the operator is intended to work with a collection of integers, allowing both reading and writing of individual items by their index.

Member Functions

Member functions, often simply called methods, are functions that belong to a class. Each class has its own set of member functions, which can either be “actions” that objects of the class can perform, or “accessors” that retrieve data from objects without altering them.

The member function for operator overloading, such as the operator[] mentioned in the exercise, is defined to perform a specific action when the corresponding operator is used on class instances. These functions are always associated with objects; when they are called, they are invoked on a particular instance of a class.

To illustrate, let's suppose one has an instance of the 'Collection' class, say myCollection, and wishes to access the 5th element, they would use myCollection[4] – wherein operator[] function is automatically called with an argument of 4. This accomplishes object-specific behavior neatly and intuitively, blending in with the built-in notions of the language.