Introduction to C++

Basic Syntax and Structure

C++ is a powerful general-purpose programming language. It is used to develop operating systems, browsers, games, and so on. C++ supports different ways of programming like procedural, object-oriented, and functional programming. In this tutorial, we will cover the basic syntax and structure of C++ programs.

1. Hello World Program

Every C++ program starts with the main() function. Let's look at a simple example:

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, World!" << endl;
    return 0;
}
                

Explanation:

• #include <iostream>: This is a preprocessor directive that includes the standard input-output stream library.
• using namespace std;: This line tells the compiler to use the standard namespace.
• int main(): This is the main function where the execution of the program begins.
• cout << "Hello, World!" << endl;: This line prints "Hello, World!" to the console.
• return 0;: This line terminates the main function and returns 0 to the operating system.

2. Variables and Data Types

Variables are used to store data in a program. Each variable in C++ has a specific type, which determines the size and layout of the variable's memory. Common data types include:

• int: Integer type.
• float: Floating point type.
• double: Double precision floating point type.
• char: Character type.
• bool: Boolean type (true or false).

Example:

#include <iostream>
using namespace std;

int main() {
    int myNum = 5;             // Integer (whole number)
    float myFloatNum = 5.99;   // Floating point number
    double myDoubleNum = 9.98; // Double floating point number
    char myLetter = 'D';       // Character
    bool myBoolean = true;     // Boolean

    cout << "Integer: " << myNum << endl;
    cout << "Float: " << myFloatNum << endl;
    cout << "Double: " << myDoubleNum << endl;
    cout << "Character: " << myLetter << endl;
    cout << "Boolean: " << myBoolean << endl;

    return 0;
}
                

3. Operators

Operators are symbols that tell the compiler to perform specific mathematical or logical operations. C++ has a rich set of operators including:

• Arithmetic Operators: +, -, *, /, %
• Comparison Operators: ==, !=, >, <, >=, <=
• Logical Operators: &&, ||, !
• Assignment Operators: =, +=, -=, *=, /=, %=

Example:

#include <iostream>
using namespace std;

int main() {
    int a = 5, b = 3;
    cout << "a + b = " << (a + b) << endl; // Arithmetic
    cout << "a == b: " << (a == b) << endl; // Comparison
    cout << "a > b: " << (a > b) << endl; // Comparison
    cout << "a && b: " << (a && b) << endl; // Logical
    a += b; // Assignment
    cout << "After a += b, a = " << a << endl;

    return 0;
}
                

4. Control Structures

Control structures allow you to control the flow of execution of the program. Common control structures include:

• Conditional Statements: if, else, else if
• Loops: for, while, do-while

Example:

#include <iostream>
using namespace std;

int main() {
    // if-else statement
    int x = 10;
    if (x > 5) {
        cout << "x is greater than 5" << endl;
    } else {
        cout << "x is not greater than 5" << endl;
    }

    // for loop
    cout << "For Loop: ";
    for (int i = 0; i < 5; ++i) {
        cout << i << " ";
    }
    cout << endl;

    // while loop
    cout << "While Loop: ";
    int j = 0;
    while (j < 5) {
        cout << j << " ";
        ++j;
    }
    cout << endl;

    return 0;
}
                

5. Functions

Functions are blocks of code that perform a specific task. They help in breaking down the program into smaller, manageable parts. A function in C++ is defined as:

#include <iostream>
using namespace std;

// Function declaration
void sayHello();

int main() {
    // Function call
    sayHello();
    return 0;
}

// Function definition
void sayHello() {
    cout << "Hello from the function!" << endl;
}
                

Explanation:

• void sayHello();: Function declaration.
• sayHello();: Function call.
• void sayHello() { ... }: Function definition.