1 Line Concepts in C++

1. Basics of C++

Basics of C++ refers to understanding the fundamental syntax, data types, operators, and control structures of the C++ language.

1.1 Syntax

C++ syntax includes the rules and conventions that define the structure of the C++ programming language.

1.2 Data Types

Data types in C++ refer to the different types of data that can be used in the program, such as int for integers, float for floating-point numbers, and char for characters.

1.3 Operators

Operators in C++ are symbols that perform operations on variables and values. Examples include '+' for addition, '-' for subtraction, '*' for multiplication, and '/' for division.

1.4 Control Structures

Control structures in C++ manage the flow of a program. They include loops (for, while, do-while) and conditionals (if, else if, else, switch-case).

2. Classes and Objects

A class in C++ is a blueprint for creating objects (a particular data structure), providing initial values for state (member variables) and implementations of behavior (member functions, also known as methods).

class ClassName {
  // member variables
  // member functions
};

2.1 Class Declaration

Class declaration involves defining the class name and the data members and member functions inside it.

class ClassName {
  int dataMember1;
  char dataMember2;
  void memberFunction1() {}
};

2.2 Object Creation

Object creation is the process of declaring an instance of a class.

ClassName objectName;

3. Inheritance

Inheritance in C++ is a process of creating new classes from existing ones, which allows for code reusability and is a key feature of OOP.

class DerivedClass: public BaseClass {
};

3.1 Single Inheritance

Single inheritance is when a class inherits from a single base class.

class DerivedClass: public BaseClass {
};

3.2 Multiple Inheritance

Multiple inheritance is when a class inherits from more than one base class.

class DerivedClass: public BaseClass1, public BaseClass2 {
};

3.3 Multilevel Inheritance

Multilevel inheritance is when a class inherits from a base class, which in turn inherits from another base class.

class DerivedClass1: public BaseClass {
};
class DerivedClass2: public DerivedClass1 {
};

3.4 Hierarchical Inheritance

Hierarchical inheritance is when one base class is inherited by more than one derived class.

class DerivedClass1: public BaseClass {
};
class DerivedClass2: public BaseClass {
};

3.5 Hybrid Inheritance

Hybrid inheritance is a combination of more than one types of inheritance.

class DerivedClass1: public BaseClass1, public BaseClass2 {
};
class DerivedClass2: public DerivedClass1 {
};

4. Polymorphism

Polymorphism is a concept where a function behaves differently in different contexts. It includes function overloading and operator overloading (compile-time polymorphism), and virtual functions (runtime polymorphism).

4.1 Function Overloading

Function overloading is the ability of a function to perform different tasks, depending on the number or type of arguments.

void functionName(int a) {}
void functionName(double a) {}

4.2 Operator Overloading

Operator overloading allows operators to have user-defined meanings on user-defined types (classes).

ClassName operator+(const ClassName&)

4.3 Virtual Functions

Virtual functions are used in a class hierarchy and can be overridden in derived classes to ensure the correct function is called for an object, regardless of the type of reference (or pointer) used for function call.

virtual returnType functionName(ArgumentType);

5. Encapsulation

Encapsulation in C++ is the idea of bundling data and functions into a single unit (a class), and restricting access to the data (using access modifiers like public, private, and protected).

class ClassName {
  private:
    int data;
  public:
    void setData(int a) {
        data = a;
    }
    int getData() {
        return data;
    }
};

6. Abstraction

Abstraction in C++ is a concept that allows hiding complex implementation details and providing a simple interface for users. It can be achieved using abstract classes and interfaces.

6.1 Abstract Classes

An abstract class is a class that has at least one pure virtual function, and cannot be instantiated.

class AbstractClass {
  virtual void functionName() = 0; // Pure virtual function
};

7. Constructors and Destructors

Constructors and destructors in C++ are special member functions of a class that are automatically called when objects are created and destroyed.

7.1 Constructors

A constructor is a special function that initializes an object. They have the same name as the class and have no return type. There are three types of constructors: default, parameterized, and copy constructors.

class ClassName {
  ClassName() {} // Default constructor
  ClassName(int a) {} // Parameterized constructor
  ClassName(const ClassName& obj) {} // Copy constructor
};

7.2 Destructors

A destructor is a special function that is called when an object goes out of scope. It has the same name as the class, preceded by a tilde (~).

class ClassName {
  ~ClassName() {} // Destructor
};

8. Exception Handling

Exception handling in C++ involves dealing with runtime errors using try, catch, and throw blocks.

try {
  // Code that might throw an exception
} catch (ExceptionType1 ex1) {
  // Code to handle exception of type ExceptionType1
} catch (ExceptionType2 ex2) {
  // Code to handle exception of type ExceptionType2
}

9. File Handling

File handling in C++ involves reading from and writing to files.

fstream file;
file.open("example.txt", ios::out); // Writing to a file
file << "Writing to a file.";
file.close();

file.open("example.txt", ios::in); // Reading from a file
char ch;
while (file >> ch) {
  cout << ch;
}
file.close();

10. Templates

Templates in C++ allow functions and classes to operate with generic types, allowing for more reusable and flexible code.

10.1 Function Templates

Function templates are functions that can be used with any data type.

template <typename T>
T functionName(T a, T b) {
  return a + b;
}

10.2 Class Templates

Class templates allow classes to have members that use template parameters as types.

template <typename T>
class ClassName {
  T data;
  public:
    ClassName(T a) {
        data = a;
    }
    T getData() {
        return data;
    }
};

11. STL - Standard Template Library

The STL is a library in C++ that provides several generic classes and functions, including containers, algorithms, iterators, and function objects.

11.1 Containers

Containers in the STL are classes that can hold and manage collections of elements. They include vector, list, deque, set, map, etc.

11.2 Algorithms

Algorithms in the STL are functions for processing sequences of elements. They include sort, reverse, find, etc.

11.3 Iterators

Iterators in the STL are used to iterate through elements of containers.

11.4 Function Objects

Function objects, also known as functors, are objects that can be called as if they are functions.

12. Memory Management

Memory management in C++ involves managing the memory allocated to your application, including allocation (using new), deallocation (using delete), and the concept of stack and heap.

12.1 Stack and Heap

The stack is used for static memory allocation and the heap is used for dynamic memory allocation.

13. OOP Design Principles

OOP Design Principles guide the design of object-oriented software, including Single Responsibility Principle, Open-Closed Principle, Liskov Substitution Principle, Interface Segregation Principle, and Dependency Inversion Principle.

13.1 Single Responsibility Principle

Single Responsibility Principle states that a class should have one, and only one, reason to change.

13.2 Open-Closed Principle

Open-Closed Principle states that software entities should be open for extension but closed for modification.

13.3 Liskov Substitution Principle

Liskov Substitution Principle states that functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it.

13.4 Interface Segregation Principle

Interface Segregation Principle states that clients should not be forced to depend on interfaces they do not use.

13.5 Dependency Inversion Principle

Dependency Inversion Principle states that high-level modules should not depend on low-level modules, both should depend on abstractions.

14. Binding

Binding in C++ refers to the process of associating a method call to the method body. It includes early (static) binding and late (dynamic) binding.

14.1 Early Binding (Static Binding)

Early binding in C++ is when the compiler directly associates a function call with the function to be executed. It includes function overloading and operator overloading.

14.2 Late Binding (Dynamic Binding)

Late binding in C++ is when the compiler is unable to associate a function call with the function to be executed. The correct function to be executed is determined at runtime. This includes the use of virtual functions.

15. Advanced Topics

Advanced topics in C++ include a variety of complex programming techniques and constructs.

15.1 Friend Classes and Functions

A friend function in C++ is a function that can access the private and protected members of a class as if it were a member of that class. A friend class is a class whose members have such access.

class ClassName {
  friend class FriendClass;
  friend void friendFunction(ClassName&);
};

15.2 Virtual Destructors

A virtual destructor in C++ ensures that the destructors for derived classes are called properly when an object is deleted through a base-class pointer.

class BaseClass {
  virtual ~BaseClass() {}
};

15.3 Smart Pointers

Smart pointers in C++ are a type of pointer that provides enhanced memory management features, like automatic deletion when no longer in use.

std::unique_ptr ptr(new ClassName);

15.4 Lambda Expressions

A lambda expression in C++ is an anonymous function that can be used to create anonymous objects for short sections of code.

auto lambda = [](int a, int b) { return a + b; };

15.5 Multithreading

Multithreading is a specialized form of multitasking that allows multiple threads of execution to run concurrently within a single program.

#include <thread>

void function_name() {
    // thread function code
}

std::thread t1(function_name);  // t1 starts running
t1.join();  // main thread waits for t1 to finish

15.6 Exception Handling

Exception handling in C++ involves identifying and handling potential runtime errors.

try {
  // code here
}
catch (const std::exception& e) {
  // catch and handle exception here
}

15.7 NameSpaces

Namespaces in C++ are used to organize code into logical groups and to prevent name collisions that can occur especially when your code base includes multiple libraries.

namespace namespace_name {
  // code here
}

15.8 Regular Expressions

Regular expressions provide a concise and flexible means for matching strings of text, such as particular characters, words, or patterns of characters.

#include <regex>

std::string s ("subject");
std::regex e ("(sub)(.*)");   // matches words beginning by "sub"
std::cout << std::regex_replace (s,e,"replace") << std::endl;

15.9 RAII (Resource Acquisition Is Initialization)

RAII is a programming idiom used in several object-oriented, statically-typed programming languages to describe a particular language behavior. In RAII, holding a resource is tied to object lifetime: resource allocation (acquisition) is done during object creation (specifically initialization), by the constructor, while resource deallocation (release) is done during object destruction, by the destructor.

15.10 Move Semantics and Rvalue References

Move semantics is a way to avoid expensive deep copy operations and improve performance by simply transferring the resources of one object to another. Rvalue references are a type of reference that can only bind to temporary objects.

ClassName(ClassName&& other) { // Move constructor
  // steal the resources of other
}

ClassName& operator=(ClassName&& other) { // Move assignment
  if (this != &other) {
    // release any resources this object is holding
    // steal the resources of other
  }
  return *this;
}

15.11 Core Object Concepts

Understanding core object concepts such as encapsulation, abstraction, polymorphism, classes, messages, association, and interfaces is essential for object-oriented programming.

15.12 Arrays as Class Member Data

Arrays can be defined as member data within classes, and the arrays can contain objects of another class. These arrays can be manipulated via member functions.

15.13 Data Conversions

Data conversion in C++ is the process of converting one data type to another. This can be done explicitly using type casting, or implicitly by the compiler.

15.14 Pitfalls of Operator Overloading and Conversion

While operator overloading can increase the readability and performance of your program, misuse can lead to confusion and errors. Similarly, data conversion can cause loss of data or precision if not used carefully.

15.15 Aggregation

Aggregation in C++ is a process where one class defines another class as any entity reference. It is another way to reuse the class. It is a form of association that represents HAS-A relationship.

15.16 Class Hierarchies

Class hierarchies are a way of organizing classes where one class inherits characteristics from one or more classes.

15.17 Public and Private Inheritance

Public inheritance means the public and protected members of the base class listed after the specifier keep their access permissions. Private inheritance means all public and protected members of the base class are private to the derived class.

15.18 The Address-of Operator

The address-of operator (&) in C++ is used to get the memory address of a variable.

int var = 5;
std::cout << &var;  // Outputs the memory address of var

15.19 Memory Management: New and Delete

The new operator is used to allocate memory dynamically on the heap for the object/variable. Conversely, the delete operator is used to deallocate memory from the heap.

int* ptr = new int; // Allocation
delete ptr;  // Deallocation

15.20 Friend Functions and Static Functions

A friend function is a function that has access to the private and protected members of a class. A static function is a function that belongs to the class rather than any object of the class.

15.21 Disk File I/O with Streams

Disk File I/O with streams involves reading from or writing to a file on the disk using stream operations.

std::ifstream inFile("input.txt");  // Create an input file stream
std::ofstream outFile("output.txt");  // Create an output file stream

15.22 Error Handling in File I/O

Error handling in file I/O involves checking whether a file was successfully opened before attempting to read from or write to it, and handling errors appropriately when they do occur.

15.23 Memory as a Stream Object

Memory can be used as a stream object through the use of stringstream in C++.

std::stringstream ss;
ss << "Example of memory as a stream";

15.24 Command Line Arguments

Command line arguments are parameters provided at the command line when running a program. These arguments are used to control the program from outside instead of hard coding those values inside the code.

In Short,