In C++, a program is a collection of objects that interact by calling each other's methods. Let's break down the fundamental terms: class, object, methods, and instance variables.

Objects: Objects in C++ have states (like color, name, breed) and behaviors (wagging, barking, eating). Think of a dog - its color, name, and breed represent states, while actions like wagging its tail and barking are behaviors. An object is an instance of a class.

Class: A class is like a blueprint or template that defines the behaviors and states supported by objects of its type.

Methods: Methods are the behaviors defined within a class. A class can have multiple methods where the actual logics and actions are written, allowing objects to perform actions.

Instance Variables: Every object possesses a unique set of instance variables that define its state. These variables are assigned specific values, determining an object's state.

C++ Program Structure: Let's examine a simple program that prints "Hello World."

cpp Copy code

#include using namespace std;

int main() { cout << "Hello World"; // prints Hello World return 0; } Key Parts of the Program: We include the header which contains necessary information. using namespace std; tells the compiler to use the std namespace. int main() is where program execution begins. cout << "Hello World"; prints the message "Hello World". return 0; terminates the main() function and returns the value 0 to the calling process. Semicolons and Blocks: In C++, a semicolon ends a statement, and blocks are logically connected statements enclosed within curly braces.

C++ Identifiers: Identifiers in C++ are names used for variables, functions, classes, etc. They start with a letter (A-Z or a-z) or an underscore, followed by letters, underscores, and digits.

C++ Keywords: Certain words in C++ are reserved and cannot be used as identifiers. These keywords serve specific purposes in the language and cannot be used for variable names or other identifiers.

Whitespace in C++: Whitespace includes blanks, tabs, newline characters, and comments. It separates different parts of a statement and aids in readability. A line with only whitespace is a blank line and is ignored by the compiler.