C++ Interface

In C++, there is no direct construct for creating interfaces like in some other programming languages such as Java. However, you can achieve a similar concept of interfaces through a combination of abstract classes and pure virtual functions.

An interface defines a contract that specifies a set of methods that a class must implement. It allows for polymorphism and ensures that objects of different classes that implement the same interface can be treated interchangeably.

Here's an example of creating an interface-like structure in C++:

class Printable {
public:
    virtual void print() const = 0;
};

class Car : public Printable {
public:
    void print() const override {
        cout << "This is a car." << endl;
    }
};

class Person : public Printable {
public:
    void print() const override {
        cout << "This is a person." << endl;
    }
};

int main() {
    Car car;
    Person person;

    Printable* printable1 = &car;
    Printable* printable2 = &person;

    printable1->print();    // Calls the print() function of Car
    printable2->print();    // Calls the print() function of Person

    return 0;
}

In the example above, the Printable class acts as an interface by declaring a pure virtual function print(). A pure virtual function is defined by using the = 0 syntax, indicating that the function has no implementation in the base class and must be overridden by derived classes.

The Car and Person classes inherit from Printable and provide their own implementations of the print() function. Objects of the derived classes can be treated as objects of the Printable interface, allowing polymorphic behavior.

By defining the Printable class with a pure virtual function, you ensure that any class inheriting from it must implement the print() function. This enforces the contract defined by the interface-like structure.

It's important to note that the term "interface" in C++ is not a language keyword but rather a design concept. By using abstract classes and pure virtual functions, you can achieve a similar effect to interfaces in other languages, allowing for the definition of contracts and providing a common interface for different classes.