C++ Basics: First Program Overview

Study Notes

First C++ Program: Printing a Line of Text

The provided program demonstrates basic C++ syntax and features.
Lines 1-11 constitute the source code, with line numbers excluded.
Comments are denoted by //, which indicates that the remaining part of the line is a comment.
Comments assist in documenting programs and enhancing readability for others.
Comments are ignored by the C++ compiler during execution.
The comment "Text-printing program" describes the program's purpose.

#include Preprocessor Directive

The #include directive signals the C++ preprocessor to incorporate the contents of the specified header file.
Header files provide vital information for compilation.
The line #include <iostream> incorporates the input/output stream header file, essential for programs using keyboard input or screen output.

The main Function

The main function is crucial for every C++ program.
The parentheses following main indicate it's a function, a fundamental building block in C++.
C++ programs typically comprise one or more functions and classes.
The program execution always begins at the main function, even if it's not the first function defined.
The keyword int preceding main signifies that the function returns an integer (whole number) value.
Braces ({ }) enclose the function's body, marking its beginning and end.

An Output Statement

The statement std::cout << “Welcome to C++ programming!” << std::endl; is responsible for printing the output.
std::cout is the standard output stream, typically directed to the console.
The << operator sends information to the output stream.
std::endl inserts a newline character, advancing the cursor to the beginning of the next line.

Modifying Our First C++ Program

The addition of a user input statement allows the program to interact with the user.
The std::cin object allows input from the standard input stream, usually the keyboard.
The >> operator extracts data from the input stream.

Another C++ Program: Adding Integers

This program calculates the sum of two integers provided by the user.
The int data type is used to store integers, which represent whole numbers.
In-depth explanation of Arithmetic Operators:
- The = operator (assignment operator) assigns the value of the expression on its right to the variable on its left.
- The + operator (addition operator) adds the two operands (numbers) it operates upon.
Variables are declared, such as number1, number2, and sum, to hold values during program execution.
The program requests the user to enter two integers.
The entered values are stored in the variables number1 and number2.
The sum of number1 and number2 is calculated and stored in the variable sum.
The program displays the calculated sum on the screen.
The std::cout << "The sum is: " << sum << std::endl; statement displays the result.
In this statement, the << operator is used to send the string "The sum is: ", the value of the sum variable, and a newline character to the output stream.
The use of std::endl ensures that the program's output appears on a separate line from any subsequent output.

Memory Concepts

Variables are allocated memory locations to store data.
Memory is divided into different segments.
The data segment stores initialized variables.
The stack segment stores local variables during function execution.
The heap segment is used for dynamic memory allocation.

Arithmetic

Arithmetic operations are performed within the program using operators such as +, -, *, /, and %.
Additional arithmetic operators are available, including ++ (increment), -- (decrement), and % (modulus).

Illustrative Example

#include <iostream>

int main() {
    int number1, number2, sum; // Declare variables

    std::cout << "Enter first integer: "; // Prompt for input
    std::cin >> number1; // Read first integer

    std::cout << "Enter second integer: "; // Prompt for input 
    std::cin >> number2; // Read second integer

    sum = number1 + number2; // Calculate the sum

    std::cout << "The sum is: " << sum << std::endl; // Display the sum

    return 0;
}