C++ Internal Problems - Solutions and Explanations

1️⃣ Employee Department Tag (object + "HR")


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

class Employee {
    string name;
    int empID;

public:
    Employee(string n, int id) {
        name = n;
        empID = id;
    }

    Employee operator+(string dept) {
        Employee temp = *this;
        temp.name = name + " (" + dept + ")";
        return temp;
    }

    void show() {
        cout << "Employee: " << name << ", ID: " << empID << endl;
    }
};

int main() {
    Employee e1("Sumit", 202);
    Employee e2 = e1 + "HR";

    e1.show();
    e2.show();
    return 0;
}

Explanation: Operator + adds a department tag to the employee name (object + string).

2️⃣ Employee Department Tag ("DEPT: " + object)


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

class Employee {
    string name;
    int empID;

public:
    Employee(string n, int id) {
        name = n;
        empID = id;
    }

    friend Employee operator+(string dept, Employee e) {
        Employee temp = e;
        temp.name = dept + e.name;
        return temp;
    }

    void show() {
        cout << "Employee: " << name << ", ID: " << empID << endl;
    }
};

int main() {
    Employee e1("Sumit", 202);
    Employee e2 = string("DEPT: ") + e1;

    e1.show();
    e2.show();
    return 0;
}

Explanation: Friend function handles string + object syntax since the left operand is not an Employee.

3️⃣ Article Class (operator overloading +, -, *, /)


#include <iostream>
using namespace std;

class article {
    double price;

public:
    article(double p = 0) { price = p; }

    article operator+(double val) { return article(price + val); }
    article operator-(double val) { return article(price - val); }
    article operator*(double val) { return article(price * val); }
    article operator/(double val) { return article(price / val); }

    friend article operator-(double val, article a) {
        return article(val - a.price);
    }

    void showarticle() {
        cout << "Article Price: " << price << " Rs" << endl;
    }
};

int main() {
    article art(1000);
    article a1 = art + 500;
    article a2 = art - 500;
    article a3 = art * 2;
    article a4 = art / 2;
    article a5 = 500 - art;

    cout << "After + : "; a1.showarticle();
    cout << "After - : "; a2.showarticle();
    cout << "After * : "; a3.showarticle();
    cout << "After / : "; a4.showarticle();
    cout << "Result of 500 - art: "; a5.showarticle();
    return 0;
}

Explanation: Shows arithmetic operator overloading and use of a friend function for value - object.

4️⃣ Velocity Class (Arithmetic Operator Overloading)


#include <iostream>
using namespace std;

class velocity {
    double speed;

public:
    velocity(double s = 0) { speed = s; }

    velocity operator+(int val) { return velocity(speed + val); }
    velocity operator-(int val) { return velocity(speed - val); }
    velocity operator*(int val) { return velocity(speed * val); }
    velocity operator/(int val) { return velocity(speed / val); }

    friend velocity operator+(int val, velocity v) {
        return velocity(val + v.speed);
    }

    void showvelocity() {
        cout << "Velocity: " << speed << " kmph" << endl;
    }
};

int main() {
    velocity v1(60);
    velocity v2 = v1 + 20;
    velocity v3 = v1 - 10;
    velocity v4 = v1 * 2;
    velocity v5 = v1 / 2;
    velocity v6 = 5 + v1;

    cout << "After + : "; v2.showvelocity();
    cout << "After - : "; v3.showvelocity();
    cout << "After * : "; v4.showvelocity();
    cout << "After / : "; v5.showvelocity();
    cout << "Result of 5 + v1 : "; v6.showvelocity();
    return 0;
}

Explanation: Demonstrates object + int (member) and int + object (friend) overloading.

5️⃣ File Not Found – Custom Exception


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

class FileNotFoundException {
public:
    string message;
    FileNotFoundException(string msg) { message = msg; }
};

void openFile(string filename) {
    if (filename != "data.txt") {
        throw FileNotFoundException("Error: File not found!");
    } else {
        cout << "File opened successfully." << endl;
    }
}

int main() {
    string fname;
    cout << "Enter filename: ";
    cin >> fname;

    try {
        openFile(fname);
    } catch (FileNotFoundException &e) {
        cout << e.message << endl;
    }

    return 0;
}

Explanation: Demonstrates a custom exception class and use of try-catch to handle errors.

6️⃣ Media Player – Virtual Functions and Upcasting


#include <iostream>
using namespace std;

class MediaFile {
public:
    virtual void play() {
        cout << "Playing media file..." << endl;
    }
};

class AudioFile : public MediaFile {
public:
    void play() override {
        cout << "Playing audio file..." << endl;
    }
};

class VideoFile : public MediaFile {
public:
    void play() override {
        cout << "Playing video file..." << endl;
    }
};

class FlashFile : public MediaFile {
public:
    void play() override {
        cout << "Playing Flash file..." << endl;
    }
};

int main() {
    MediaFile* mptr;
    AudioFile a;
    VideoFile v;
    FlashFile f;
    int choice;
    do {
        cout << "\\n--- Media Player Menu ---\\n";
        cout << "1. Play Audio\\n2. Play Video\\n3. Play Flash\\n4. Exit\\n";
        cout << "Enter choice: ";
        cin >> choice;

        switch (choice) {
        case 1: mptr = &a; mptr->play(); break;
        case 2: mptr = &v; mptr->play(); break;
        case 3: mptr = &f; mptr->play(); break;
        case 4: cout << "Exiting..." << endl; break;
        default: cout << "Invalid choice!" << endl;
        }
    } while (choice != 4);
    return 0;
}