Runtime Driver Selection

#include <iostream>
using namespace std;

/**
 * Base Driver Class
 * The 'virtual' keyword enables runtime polymorphism, allowing 
 * the program to decide which function to call at execution time.
 */
class Driver {
public:
    // Virtual destructor is vital for base classes to prevent memory leaks
    virtual ~Driver() {}

    // Marking this virtual allows derived classes to override behavior
    virtual void start() {
        cout << "Generic driver started" << endl;
    }
};

/**
 * SPI Implementation
 */
class SpiDriver : public Driver {
public:
    // 'override' ensures the signature matches the base class exactly
    void start() override {
        cout << "SPI driver started" << endl;
    }
};

/**
 * I2C Implementation
 */
class I2cDriver : public Driver {
public:
    void start() override {
        cout << "I2C driver started" << endl;
    }
};

int main() {
    int mode;
    if (!(cin >> mode)) return 0; // Basic input safety

    // Stack allocation to avoid dynamic memory (as per constraints)
    SpiDriver spi;
    I2cDriver i2c;

    Driver* driver = nullptr;

    // Assignment of derived address to base pointer
    if (mode == 0) {
        driver = &spi;
    } else {
        driver = &i2c;
    }

    // Now uses dynamic dispatch to call the correct derived method
    if (driver) {
        driver->start(); 
    }

    return 0;
}