C PlusPlus Programming Interview Questions

The basic concepts of object-oriented programming in C++ are:

Class: A user-defined data type that encapsulates data and functions related to a specific entity.

Object: An instance of a class that has its own state and behavior.

Inheritance: The mechanism of deriving new classes from existing ones, allowing code reuse and specialization.

Polymorphism: The ability of an object to behave differently depending on its type or context. Polymorphism can be achieved through virtual functions and function overloading.

Abstraction: The process of hiding the implementation details and exposing only the essential features of an entity.

Encapsulation: The principle of binding the data and functions together and protecting them from unauthorized access.

A constructor is a special member function of a class that is invoked automatically when an object of that class is created. A constructor has the same name as the class and does not have a return type. A constructor is used to initialize the data members of the object with some default or user-defined values.

A destructor is a special member function of a class that is invoked automatically when an object of that class is destroyed. A destructor has the same name as the class preceded by a tilde (~) and does not have a return type or parameters. A destructor is used to release the resources allocated to the object and perform any cleanup operations.

A pointer is a variable that stores the address of another variable. A pointer can be declared using the asterisk (*) symbol and can be dereferenced using the same symbol to access the value of the variable it points to. A pointer can point to any type of variable, including another pointer, and can be assigned a null value to indicate that it does not point to anything.

A reference is an alias or a nickname for another variable. A reference can be declared using the ampersand (&) symbol and does not need to be dereferenced to access the value of the variable it refers to. A reference must be initialized with a variable of the same type and cannot be changed to refer to another variable. A reference cannot be null and must always refer to a valid object.

Static binding, also known as compile-time binding or early binding, is the process of resolving the function calls at compile time. Static binding is achieved by using non-virtual functions, overloaded functions, and templates. Static binding is faster and more efficient, but less flexible and polymorphic.

Dynamic binding, also known as run-time binding or late binding, is the process of resolving the function calls at run time. Dynamic binding is achieved by using virtual functions, which are overridden in the derived classes. Dynamic binding is slower and less efficient, but more flexible and polymorphic.

Public, protected, and private are access specifiers that determine the visibility and accessibility of the data members and member functions of a class. The difference between them are:

Public: The data members and member functions declared as public are accessible from anywhere, inside or outside the class, and by the derived classes as well.

Protected: The data members and member functions declared as protected are accessible only from within the class and by the derived classes, but not from outside the class.

Private: The data members and member functions declared as private are accessible only from within the class, but not from outside the class or by the derived classes.

Overloading and overriding are two forms of polymorphism in C++. The difference between them are:

Overloading: Overloading is the process of defining multiple functions or operators with the same name but different parameters or return types. Overloading can be done for both member and non-member functions, as well as for unary and binary operators. Overloading is resolved at compile time using static binding.

Overriding: Overriding is the process of redefining a virtual function in a derived class that has already been defined in the base class. Overriding can be done only for member functions, and the parameters and return types of the overridden function must match with the base class function. Overriding is resolved at run time using dynamic binding.

Multiple and multilevel inheritance are two types of inheritance in C++. The difference between them are:

Multiple inheritance: Multiple inheritance is the process of deriving a new class from more than one base class. The new class inherits the features of all the base classes. Multiple inheritance can lead to ambiguity and complexity if the base classes have common members or methods.

Multilevel inheritance: Multilevel inheritance is the process of deriving a new class from another derived class, which in turn is derived from a base class. The new class inherits the features of both the base class and the intermediate class. Multilevel inheritance can create a hierarchy of classes with different levels of abstraction and specialization.

New and malloc are two ways of allocating memory dynamically in C++. The difference between them are:

New: New is an operator that allocates memory for a single object or an array of objects of a given type and returns a pointer to the allocated memory. New also invokes the constructor of the object to initialize it. New can be paired with delete to deallocate the memory and invoke the destructor of the object.

Malloc: Malloc is a function that allocates memory for a given number of bytes and returns a void pointer to the allocated memory. Malloc does not invoke the constructor of the object and does not initialize the memory. Malloc can be paired with free to deallocate the memory.

A class and a structure are two user-defined data types that can contain data members and member functions. The difference between them are:

Class: A class can have any access specifier for its data members and member functions. By default, the access specifier is private, which means the data members and member functions are accessible only from within the class, but not from outside the class or by the derived classes. A class can also have constructors, destructors, virtual functions, and other features of object-oriented programming.

Structure: A structure can have only public access specifier for its data members and member functions. By default, the access specifier is public, which means the data members and member functions are accessible from anywhere, inside or outside the structure, and by the derived structures as well. A structure cannot have constructors, destructors, virtual functions, or other features of object-oriented programming.