C++ Terminologies for Beginners: With daily life examples

C++ has a rich set of terminologies essential to understand when working with the language. Here are some standard terms you may encounter.

Knowing these 21 terms is enough to proceed to the next step. The next step is to delve into each topic in more depth and then start coding.

1. Class

In C++, a class is a user-defined data type that serves as a blueprint for creating objects. It defines a set of attributes (data members) and behaviors (member functions) that the objects of the class possess.

Classes support encapsulation, inheritance, and polymorphism, which are fundamental principles of object-oriented programming. 

For instance, consider a “Person” class. It can define attributes like name, age, address, and behaviors like walking, talking, or working. Objects created from this class will represent specific people, each with its own attributes and behaviors as per the class definition.

2. Struct 

A struct in C++ is similar to a class but primarily used for grouping data members under a single name. struct members have public access by default, unlike class members, who are private by default. Structs support inheritance and can have member functions, but they are typically used for passive data structures. 

For example, a “Date” struct could represent a calendar date with integer attributes for day, month, and year. Structs help organize and manage related data, making it easier to pass around and manipulate such data as a single unit in your program.

3. Namespace

Namespaces in C++ are a way to group related identifiers, such as variables, functions, classes, and structs, under a single name. This helps avoid naming conflicts and makes the code more organized and maintainable. 

For instance, imagine two libraries, each with a “File” class. By placing each class in a separate namespace, we can distinguish between them and avoid ambiguity. 

The C++ Standard Library itself uses the “std” namespace, which is why we write “std::string” or “std::vector”. 

Namespaces can be nested, and the “using” keyword allows us to access namespace members without specifying the full namespace path.

4. Template

Templates in C++ are a powerful mechanism that enables code reusability and generic programming. They allow you to create classes or functions operating on different data types without duplicating code. 

A template is defined using the “template” keyword followed by template parameters enclosed in angle brackets. 

For example, a generic “Stack” class can be created as a template to store elements of any data type. The C++ Standard Template Library (STL) heavily utilizes templates to provide reusable and efficient data structures (e.g., std::vector, std::list) and algorithms (e.g., std::sort, std::find) that work with various data types.

5. Function

Functions in C++ are a collection of statements that perform a specific task or computation. They take input in the form of arguments, process it, and return a value. Functions promote modularity and code reusability, making programs easier to understand and maintain. 

For instance, a “calculateArea” function can take the length and width of a rectangle and return its area. Functions can be overloaded, allowing them to have the same name but different parameter lists, and can also be defined as inline or recursive. 

Member functions are functions defined within a class or struct and operate on the class or struct’s data members.

6. Argument

Arguments, also known as actual parameters, are the values passed to a function when it is called. They correspond to the function’s parameters (formal parameters) and provide the input data for the function to process. 

For example, in a call to a “multiply” function, like multiply(5, 3), the numbers 5 and 3 are arguments. Arguments can be passed by value, where a copy of the value is created, or by reference.

7. Parameter

Parameters, or formal parameters, are variables declared in a function definition that represent the input values the function operates on. When a function is called, the arguments provided in the function call are assigned to the corresponding parameters. 

Parameters can be passed by value, where a copy of the argument is created, or by reference, where the function operates on the original argument directly. For example, in the function definition, “int add(int a, int b)”, ‘a’ and ‘b’ are parameters that represent the two integer values to be added together.

8. Reference

A reference in C++ is an alias for another variable or object, providing an alternative way to access and manipulate it. References are declared using the ‘&’ symbol and must be initialized when they are declared. 

Unlike pointers, references cannot be reassigned and cannot be null. References are often used in function parameters to pass arguments by reference, allowing the function to modify the original variable without making a copy. 

For example, a “swap” function can take two integer references as input and swap their values, effectively modifying the original variables provided as arguments.

9. Pointer

A pointer in C++ is a variable that stores the memory address of another variable or object. Pointers allow for efficient and flexible manipulation of memory and dynamic memory allocation. They are declared using the ‘*’ symbol and can be dereferenced using the same symbol to access the value stored at the referenced address.

Pointers are commonly used in C++ to manage arrays, pass arguments by address, and implement data structures like linked lists and trees. 

However, they also introduce the potential for memory-related issues, such as dangling pointers, memory leaks, and segmentation faults.

10. Dynamic Memory Allocation

Dynamic memory allocation in C++ refers to requesting and releasing memory during runtime, allowing for flexible memory management. The ‘new’ operator is used to allocate memory, while the ‘delete’ operator is used to release memory. 

For arrays, ‘new[]‘ and ‘delete[]‘ are used. Dynamic memory allocation is crucial when the size of data structures needs to be determined at runtime or when dealing with large amounts of data that would exceed the stack limit. 

However, it comes with potential issues like memory leaks or incorrect memory management, which can be mitigated using smart pointers or RAII techniques.

11. RAII

RAII (Resource Acquisition Is Initialization) is a programming idiom in C++ that binds resources, such as memory or file handles, to object lifetimes. This ensures proper resource management, as resources are acquired during object construction and released during object destruction. 

RAII promotes deterministic resource management, simplifies code, and helps prevent resource leaks or dangling references. 

For example, using a C++ standard library container, like ‘std::vector’, or a smart pointer, like ‘std::unique_ptr‘, automatically manages memory, ensuring that memory is released when the object goes out of scope or is destroyed.

12. Inheritance

Inheritance is a core concept in object-oriented programming that allows one class to inherit properties (data members) and methods (member functions) from another class. 

This promotes code reusability and modularity. In C++, inheritance is achieved using the ‘:’ symbol, followed by an access specifier and the base class name. Derived classes can override or extend base class functionality and introduce new properties or methods. 

Inheritance can be single or multiple and can be public, protected, or private. However, the concept of multiple inheritance should be used cautiously, as it can introduce complexity and ambiguity, like the “diamond problem.”

13. Polymorphism

Polymorphism, meaning “many forms,” is a key concept in object-oriented programming that allows a single function or method to operate on different data types or objects, providing flexibility and extensibility in code. 

In C++, polymorphism is achieved through function overloading, operator overloading, and virtual functions. Virtual functions enable runtime polymorphism, where a base class pointer or reference can be used to call the appropriate derived class function at runtime. 

This makes it easy to work with collections of related objects and extend functionality in a modular manner without modifying existing code.

14. Overloading

Overloading in C++ is the ability to define multiple functions or operators with the same name but different parameter lists, allowing for context-specific behavior. Function overloading is a form of compile-time polymorphism that enables a single function name to perform different tasks based on the number or types of arguments provided. 

Operator overloading allows custom behavior for built-in operators when used with user-defined types, like classes or structs. For example, the ‘+’ operator can be overloaded for a “Matrix” class to perform matrix addition. Properly used, overloading leads to cleaner, more intuitive, and easier-to-read code.

15. Overriding

Overriding is a concept in object-oriented programming that allows a derived class to provide a new implementation of a base class method, enabling specialized behavior. 

In C++, this is achieved by declaring a method with the same name and parameter list in the derived class as in the base class. The ‘virtual’ keyword is used in the base class method declaration to enable runtime polymorphism, allowing a base class pointer or reference to call the appropriate derived class method. 

Overriding promotes modularity and extensibility by allowing derived classes to customize or extend base class functionality.

16. Constructor

A constructor is a special member function in C++ that is called when an object is created. Its primary purpose is to initialize the object’s attributes with default or user-provided values. Constructors have the same name as the class and do not have a return type. 

They can be overloaded, allowing for different ways to initialize an object. In addition to default constructors, C++ supports parameterized constructors, copy constructors, and move constructors. 

Properly designed constructors ensure that objects are always created in a valid state, simplifying object management and improving code reliability.

17. Destructor

A destructor is a special member function in C++ that is called when an object is destroyed, either by going out of scope or by being explicitly deleted. Destructors have the same name as the class, preceded by a tilde (~), and do not have a return type or parameters. 

The primary purpose of a destructor is to perform cleanup tasks, such as releasing dynamically allocated memory, closing file handles, or disconnecting network resources. 

Properly designed destructors ensure that resources are released on time, preventing resource leaks and improving the program’s overall stability.

18. Exception

An exception in C++ is an abnormal or unexpected event that occurs during program execution, which can be caught and handled by the program. Exceptions are used to signal errors or exceptional conditions and allow for more robust and maintainable error handling. 

They are thrown using the ‘throw’ keyword and caught using ‘try’ and ‘catch’ blocks. The C++ Standard Library provides standard exception classes, like std::runtime_error or std::out_of_range, but users can also define custom exception classes. 

Properly handling exceptions helps create more reliable and fault-tolerant programs.

19. STL

The Standard Template Library (STL) is a collection of template classes and functions that provide common data structures and algorithms for C++ programming. The STL is part of the C++ Standard Library and includes containers, iterators, algorithms, and function objects. 

Containers, such as vector, list, and map, store and organize data, while iterators provide a way to traverse and access elements in containers. Algorithms, like sort and find, perform operations on container elements. The STL promotes code reusability, efficiency, and consistency across different platforms, making it a powerful tool for C++ developers.

20. Friend Function

A friend function in C++ is a function that is granted special access to a class’s private and protected members, even though it is not a member function of the class. Friend functions are declared using the ‘friend’ keyword inside the class definition. 

Friend functions can be useful for implementing functionality that requires direct access to a class’s internal data but does not logically belong to the class itself. For example, a friend function can be used to implement an overloaded stream insertion operator (<<) for a custom class, allowing for easy output of the class’s attributes.

21. Friend Class

A friend class in C++ is a class that has access to the private and protected members of another class, allowing for tighter coupling between the two classes when necessary. A class can declare another class as a friend using the ‘friend’ keyword followed by the class name inside its class definition. 

Friend classes can be useful in certain situations where a close relationship between two classes is required, such as when designing a complex data structure or implementing a specific design pattern. 

However, excessive use of friend classes can lead to less modular and maintainable code, so it should be used judiciously.