C++ Classes and Data Abstraction

Chapter 10 - Classes and Data Abstraction

• A class in C++ is a user-defined data type that encapsulates data members and member functions.
• The private access specifier makes members accessible only within the class itself and by friend functions.
• The default access specifier for members of a class is private.
• An accessor function is string getName() const.
• The primary purpose of a constructor is to initialize objects when they are created.
• Destructors are prefixed with a tilde (~) symbol.
• An Abstract Data Type (ADT) defines data and operations from a user's perspective, independent of implementation.
• The main difference between a struct and a class in C++: in structs, members are public by default; in classes, they are private by default.
• Information hiding restricts access to implementation details while exposing a controlled interface.
• A member function is automatically inlined in C++ when it is defined inside the class definition.
• A static data member in a class exists regardless of how many objects of the class have been created.

Chapter 11 - Inheritance and Composition

• Inheritance represents an Is-a relationship between classes.
• A derived class inherits characteristics from another class.
• The override keyword is recommended to use when overriding a base class member function in modern C++.
• Constructors are executed in the order of base class constructor, then derived class constructor when a derived class object is created.
• Destructors are executed in the order of derived class destructor, then base class destructor when a derived class object is destroyed.
• The base class header file should be included in a derived class header file.
• ios_base is at the root of the C++ stream class hierarchy.
• Public inheritance makes base class public members public in the derived class.
• Composition represents a Has-a relationship between classes.
• Encapsulation principle of OOD involves bundling data and methods that operate on that data.
• Inheritance OOD principle allows a class to inherit attributes and behaviors from another class.
• Polymorphism OOD principle allows objects of different classes to respond to the same method in different ways.

Chapter 12 - Pointers, Classes, Virtual Functions, and Abstract Classes

• A pointer variable stores a memory address.
• The declaration of a pointer to an integer in C++ is int *x;
• The address-of operator (&) returns the memory address of a variable.
• A member of a class is accessed through a pointer using pointer->member.
• A dynamic variable allocated on the heap during program execution.
• The new operator is used to allocate memory on the heap for a single object.
• If p is a pointer to an integer, p+2 points to the integer 2 positions away from the original location.
• A dynamic array of 10 integers is allocated using int *array = new int[10];
• Range-based for loops cannot be used with raw dynamic arrays because the size information is not available at compile time.
• When a pointer is passed to a function, the function receives a copy of the pointer.
• A shallow copy duplicates only the object's member values, not what its pointers refer to.
• The "Rule of Three" in C++ states: If a class defines any of destructor, copy constructor, or copy assignment operator, it should define all three.
• A copy constructor is called when an object is created from another object of the same class.
• The purpose of a virtual destructor is to ensure proper destruction of derived class objects when deleted through a base class pointer.
• A properly implemented copy assignment operator solves memory leaks, double deletion, and self-assignment issues.
• A function is made virtual in C++ when it is declared with the keyword "virtual".
• An abstract class in C++ is a class that cannot be instantiated, typically containing at least one pure virtual function.
• The address-of operator can be overloaded for a class to change how addresses are obtained.

Chapter 13 - Overloading and Templates

• Overloading is for functions with the same name but different parameters; overriding is for redefining inherited virtual functions.
• The scope resolution operator :: cannot be overloaded in C++.
• The "this" pointer refers to the address of the current object.
• A friend function has access to private and protected members of a class.
• Non-member function overloads are generally preferred for binary operators like + and -.
• The assignment operator is properly overloaded as ClassName& operator=(const ClassName& other);
• When overloading binary arithmetic operators as member functions, they take one parameter.
• Insertion and extraction (<< and >>) operators must be overloaded as non-member functions because the left operand is a stream object, not the class object.
• A function template is a function that can be used with arguments of different types.
• A class template for a Stack that can hold any type is declared as template <typename T> class Stack { ... };
• The "Rule of Five" adds move constructor and move assignment operator to the "Rule of Three".
• A move constructor is typically called when an object is created from an rvalue (temporary).
• A move assignment operator typically transfers ownership of resources instead of copying them, unlike a copy assignment operator.

Chapter 14 - Exception Handling

• The purpose of exception handling in C++ is to handle runtime errors in a structured way.
• The try block contains code that might throw an exception.
• std::exception is a standard C++ exception class.
• A custom exception class in C++ is created by typically deriving from std::exception or one of its subclasses.
• Re-throwing an exception means catching an exception and then throwing it again from within a catch block.
• Logging the error and continue exception handling technique continues execution after logging the error.
• Stack unwinding in exception handling is the process of destroying automatic objects and calling destructors when an exception is thrown.