15 C++ Programs for Beginners

The fastest way to learn C++ is to type small programs and run them. Below are 15 short, complete, commented programs that build from your very first line of output up to a tiny class. Each one compiles as-is with a modern C++ compiler. Read the comments, type them out yourself, then tweak them — change the numbers, add a feature, break it on purpose to see what the compiler says.

1. Hello, World

#include <iostream>

int main() {
    std::cout << "Hello, World!\n";   // print text, then a newline
    return 0;                         // 0 means "success"
}

2. Add two numbers

#include <iostream>

int main() {
    int a, b;
    std::cout << "Enter two numbers: ";
    std::cin >> a >> b;               // read two ints from the user
    std::cout << "Sum = " << (a + b) << "\n";
}

3. Even or odd

#include <iostream>

int main() {
    int n;
    std::cin >> n;
    // % gives the remainder; 0 remainder means even
    std::cout << (n % 2 == 0 ? "Even" : "Odd") << "\n";
}

4. Largest of three numbers

#include <iostream>
#include <algorithm>   // std::max

int main() {
    int a, b, c;
    std::cin >> a >> b >> c;
    int biggest = std::max({a, b, c});   // max of an initializer list
    std::cout << "Largest = " << biggest << "\n";
}

5. Factorial of a number

#include <iostream>

int main() {
    int n;
    std::cin >> n;
    unsigned long long result = 1;
    for (int i = 2; i <= n; ++i) {   // multiply 2 * 3 * ... * n
        result *= i;
    }
    std::cout << n << "! = " << result << "\n";
}

6. Check if a number is prime

#include <iostream>

int main() {
    int n;
    std::cin >> n;
    bool isPrime = (n > 1);
    for (int i = 2; i * i <= n; ++i) { // only test up to the square root
        if (n % i == 0) {
            isPrime = false;
            break;
        }
    }
    std::cout << (isPrime ? "Prime" : "Not prime") << "\n";
}

7. Sum of digits

#include <iostream>

int main() {
    int n, sum = 0;
    std::cin >> n;
    n = (n < 0) ? -n : n;        // work with the absolute value
    while (n > 0) {
        sum += n % 10;           // add the last digit
        n /= 10;                 // drop the last digit
    }
    std::cout << "Digit sum = " << sum << "\n";
}

8. Reverse a number

#include <iostream>

int main() {
    int n, reversed = 0;
    std::cin >> n;
    while (n != 0) {
        reversed = reversed * 10 + n % 10; // build the reverse digit by digit
        n /= 10;
    }
    std::cout << "Reversed = " << reversed << "\n";
}

9. Multiplication table

#include <iostream>

int main() {
    int n;
    std::cin >> n;
    for (int i = 1; i <= 10; ++i) {
        std::cout << n << " x " << i << " = " << (n * i) << "\n";
    }
}

10. Fibonacci series

#include <iostream>

int main() {
    int count;
    std::cin >> count;
    long long a = 0, b = 1;
    for (int i = 0; i < count; ++i) {
        std::cout << a << " ";
        long long next = a + b;   // each term is the sum of the previous two
        a = b;
        b = next;
    }
    std::cout << "\n";
}

11. Swap two numbers (with std::swap)

#include <iostream>
#include <utility>   // std::swap

int main() {
    int x = 5, y = 9;
    std::swap(x, y);             // clean, standard way to swap
    std::cout << "x=" << x << " y=" << y << "\n";  // x=9 y=5
}

12. Count vowels in a string

#include <iostream>
#include <string>

int main() {
    std::string text;
    std::getline(std::cin, text);
    int vowels = 0;
    for (char c : text) {
        char lower = std::tolower(static_cast<unsigned char>(c));
        if (lower == 'a' || lower == 'e' || lower == 'i'
            || lower == 'o' || lower == 'u') {
            ++vowels;
        }
    }
    std::cout << "Vowels: " << vowels << "\n";
}

13. Palindrome check

#include <iostream>
#include <string>
#include <algorithm>

int main() {
    std::string s;
    std::cin >> s;
    std::string reversed = s;
    std::reverse(reversed.begin(), reversed.end()); // reverse a copy
    std::cout << (s == reversed ? "Palindrome" : "Not a palindrome") << "\n";
}

14. Average of numbers in a vector

#include <iostream>
#include <vector>
#include <numeric>   // std::accumulate

int main() {
    std::vector<int> marks{72, 95, 60, 88};
    int total = std::accumulate(marks.begin(), marks.end(), 0); // sum
    double average = static_cast<double>(total) / marks.size();
    std::cout << "Average = " << average << "\n";
}

15. A simple class

#include <iostream>
#include <string>

class Rectangle {
    double width, height;          // private data
public:
    Rectangle(double w, double h) : width(w), height(h) {}
    double area() const { return width * height; }
};

int main() {
    Rectangle r{3.0, 4.0};
    std::cout << "Area = " << r.area() << "\n";   // 12
}

How to practise these well

• Type them, do not copy-paste. The muscle memory of writing #include and std::cout is part of learning.
• Compile after every change so you catch errors while they are small.
• Modify each program. Make the factorial handle 0, make the prime checker print all primes up to N, make the class add a perimeter().
• Read the compiler errors. They are your fastest teacher.

Common mistakes

• Forgetting #include. Each feature needs its header — <iostream> for I/O, <vector> for vectors, <string> for strings, <algorithm> for sort/reverse.
• Reading input wrong. std::cin >> s stops at the first space; use std::getline when you want a whole line.
• Integer division surprises. 7 / 2 is 3, not 3.5. Cast to double (as in program 14) for real division.
• Off-by-one loops. Decide carefully between < and <= in your loop conditions.

FAQ

What is the best first C++ program to write? Start with Hello World (program 1). It confirms your compiler works and teaches the structure of main() and std::cout.

Do I need to memorise these? No. Understand the logic, then re-derive them. The patterns — loops, conditionals, accumulating a result — matter far more than any single program.

Keep learning

• Ready for objects? Start with Classes & Objects in C++.
• Use the resizable arrays from program 14 in depth in Vectors in C++.
• Browse every topic on the C++ OOP hub.

Turn these exercises into real projects with mentors in Jalgaon — join the waitlist for our C++ Programming course.