What are some examples of variance in C++?

Can you explain what variance means in C++?

Variance in C++ refers to how subtypes relate to their supertypes, particularly in the context of templates and inheritance.

Can you give me some examples of variance in C++?

Sure! For example, if you have a base class Shape and derived classes Circle and Square, you can use variance when working with pointers or references to these classes.

What about covariance and contravariance?

Covariance allows a derived type to be substituted for a base type, while contravariance allows a base type to be substituted for a derived type, especially in function parameters.

Can you show me a code example?

Certainly! Here's a simple example:

class Shape {};
class Circle : public Shape {};
class Square : public Shape {};

void draw(Shape* s) { /* drawing logic */ }

void drawCircle(Circle* c) {
    draw(c); // This is covariance
}