What are the differences between abstract classes and interfaces in C++?

What are the differences between abstract classes and interfaces in C++?

In C++, abstract classes can have both abstract and concrete methods, while interfaces can only have pure virtual methods.

Can you give me an example of an abstract class?

Sure! An abstract class in C++ might look like this:

class Shape {
public:
    virtual void draw() = 0; // pure virtual function
};

And how about an interface?

In C++, an interface is typically defined as a class with only pure virtual functions:

class Drawable {
public:
    virtual void draw() = 0;
};

Are there any performance differences between using them?

Generally, the performance difference is negligible, but abstract classes can have some overhead due to potential concrete methods.