What is the role of constexpr in C++ classes?

What is the role of constexpr in C++ classes?

In C++, constexpr allows you to define functions and variables that can be evaluated at compile time, enhancing performance.

Can you give me an example of using constexpr in a class?

Sure! Here's a simple example:

class Circle {
public:
    constexpr Circle(double r) : radius(r) {}
    constexpr double area() const { return 3.14159 * radius * radius; }
private:
    double radius;
};

This class defines a Circle with a constexpr constructor and a constexpr method to calculate the area.

Are there any limitations to using constexpr?

Yes, constexpr functions must have a return type and cannot contain any statements that are not allowed in constant expressions, like dynamic memory allocation.

How does constexpr improve performance?

By evaluating expressions at compile time, constexpr reduces runtime overhead, leading to faster execution and less memory usage.