C++ Practice Programs: 50+ Solved University Lab Exercises & Real-World Code

Theory without hands-on practice is incomplete. Here is a curated, categorized master library of 50+ classic and modern C++ programs with full source code, detailed logic walkthroughs, and expected terminal outputs. Ideal for BCA, B.Sc. IT, B.Tech CS semester exams, and competitive programming beginners.

Category A: Core Fundamentals & Math

Program 1: Check Palindrome Number

#include <iostream>

int main() {
    int n = 12321, original = n, reversed = 0;
    while (n > 0) {
        reversed = (reversed * 10) + (n % 10);
        n /= 10;
    }
    if (original == reversed) {
        std::cout << original << " is a Palindrome Number!\n";
    } else {
        std::cout << original << " is NOT a palindrome.\n";
    }
    return 0;
}

Program 2: Prime Number Generator within Range [1, N]

#include <iostream>
#include <vector>

bool isPrime(int n) {
    if (n <= 1) return false;
    for (int i = 2; i * i <= n; ++i) {
        if (n % i == 0) return false;
    }
    return true;
}

int main() {
    int limit = 20;
    std::cout << "Primes up to " << limit << ": ";
    for (int i = 2; i <= limit; ++i) {
        if (isPrime(i)) std::cout << i << " ";
    }
    std::cout << "\n";
    return 0;
}

Category B: Arrays, Matrices & Strings

Program 3: 2D Matrix Multiplication ($3 \times 3$)

#include <iostream>

int main() {
    int A[2][2] = {{1, 2}, {3, 4}};
    int B[2][2] = {{5, 6}, {7, 8}};
    int C[2][2] = {0};

    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < 2; ++j) {
            for (int k = 0; k < 2; ++k) {
                C[i][j] += A[i][k] * B[k][j];
            }
        }
    }

    std::cout << "Matrix Multiplication Result:\n";
    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < 2; ++j) {
            std::cout << C[i][j] << " ";
        }
        std::cout << "\n";
    }
    return 0;
}

Category C: Object-Oriented Programming (OOP) Labs

Program 4: University Student Records with Constructors

#include <iostream>
#include <string>
#include <vector>

class Student {
private:
    int roll;
    std::string name;
    float marks[3];

public:
    Student(int r, std::string n, float m1, float m2, float m3) 
        : roll(r), name(n) {
        marks[0] = m1; marks[1] = m2; marks[2] = m3;
    }

    float getAverage() const {
        return (marks[0] + marks[1] + marks[2]) / 3.0f;
    }

    void display() const {
        std::cout << "Roll: " << roll << " | Name: " << name 
                  << " | Avg: " << getAverage() << "\n";
    }
};

int main() {
    std::vector<Student> roster = {
        Student(101, "Aarav Sharma", 88.5, 92.0, 79.5),
        Student(102, "Priya Patel", 95.0, 94.5, 98.0)
    };

    std::cout << "--- Student Grade Summary ---\n";
    for (const auto& s : roster) {
        s.display();
    }
    return 0;
}

Program 5: Polymorphic Area Calculator (Pure Virtual Functions)

#include <iostream>
#include <memory>
#include <vector>

class Shape {
public:
    virtual double area() const = 0; // Pure virtual
    virtual ~Shape() = default;
};

class Rectangle : public Shape {
    double w, h;
public:
    Rectangle(double width, double height) : w(width), h(height) {}
    double area() const override { return w * h; }
};

class Circle : public Shape {
    double r;
public:
    Circle(double radius) : r(radius) {}
    double area() const override { return 3.14159 * r * r; }
};

int main() {
    std::vector<std::unique_ptr<Shape>> shapes;
    shapes.push_back(std::make_unique<Rectangle>(10.0, 5.0));
    shapes.push_back(std::make_unique<Circle>(7.0));

    for (const auto& s : shapes) {
        std::cout << "Calculated Area: " << s->area() << "\n";
    }
    return 0;
}