C++ — Get Started

What is C++?

C++ is a powerful general-purpose language built on top of C. Created by Bjarne Stroustrup in 1983, it adds object-oriented programming, templates, and the Standard Template Library (STL) while retaining C's performance.

C++ powers game engines (Unreal), browsers (Chrome), databases (MySQL), operating systems (Windows parts), and high-performance computing.

Install a compiler

You need a C++ compiler. The most common is g++ (part of GCC):

Windows

1. Install MinGW-w64
2. Add the bin folder to your PATH
3. Verify: g++ --version

Mac

xcode-select --install

Linux

sudo apt install g++

Your first program

Create hello.cpp:

#include <iostream>

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

Compile and run:

g++ hello.cpp -o hello
./hello

Output:

Hello, world!

Understanding the code

#include <iostream>    // includes the I/O stream library

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

• std::cout — standard output (console)
• << — stream insertion operator (sends data to the output)
• std::endl — newline and flush
• return 0 — success

C++ vs C

C++ builds on C but adds significant features:

Feature	C	C++
Output	printf()	std::cout
Input	scanf()	std::cin
Memory	malloc/free	new/delete, smart pointers
Classes	No	Yes
Templates	No	Yes
STL	No	Yes

Using namespace std

#include <iostream>
using namespace std;

int main() {
    cout << "No std:: prefix needed!" << endl;
    return 0;
}

using namespace std brings all standard names into scope. Fine for learning; avoid in large projects to prevent naming conflicts.

Variables

#include <iostream>
using namespace std;

int main() {
    int age = 36;
    double pi = 3.14159;
    char letter = 'A';
    string name = "Ada";     // C++ string
    bool active = true;

    cout << "Name: " << name << endl;
    cout << "Age: " << age << endl;
    cout << "Pi: " << pi << endl;
    cout << "Letter: " << letter << endl;
    cout << "Active: " << active << endl;

    return 0;
}

C++ adds string, bool, and other types beyond C's basic set.

Input with cin

#include <iostream>
#include <string>
using namespace std;

int main() {
    string name;
    int age;

    cout << "Enter your name: ";
    getline(cin, name);

    cout << "Enter your age: ";
    cin >> age;

    cout << "Hello, " << name << "! You are " << age << " years old." << endl;

    return 0;
}

cin >> reads until whitespace. getline(cin, name) reads an entire line.

auto keyword

C++11 introduced auto for type inference:

auto x = 42;        // int
auto pi = 3.14;     // double
auto name = string("Ada");  // string
auto active = true;  // bool

Use auto when the type is obvious from context.

constexpr

constexpr int MAX_SIZE = 100;
constexpr double PI = 3.14159265358979;

constexpr values are computed at compile time — they're constants that the compiler can optimize.

C++11/14/17/20 features

Modern C++ is much easier to learn than old C++:

// Range-based for loop (C++11)
vector<int> nums = {1, 2, 3, 4, 5};
for (auto n : nums) {
    cout << n << " ";
}

// Structured bindings (C++17)
auto [name, age] = make_pair("Ada", 36);

// Optional (C++17)
optional<int> maybe = 42;
if (maybe.has_value()) {
    cout << maybe.value() << endl;
}

Useful compiler flags

g++ -Wall -std=c++17 -o program source.cpp

• -Wall — enable all warnings
• -std=c++17 — use C++17 standard
• -O2 — optimize for speed
• -g — include debug information

Mini Practice

1. Install g++ and verify with g++ --version
2. Write a program that reads two numbers and prints their sum
3. Use auto to declare variables of different types
4. Create a range-based for loop that prints elements of a vector
5. Use constexpr for a mathematical constant

Next: C++ syntax rules →