What are some examples of using constexpr in C++?

Can you give me some examples of using constexpr in C++?

Sure! In C++, constexpr is used to declare that it's possible for the value of a variable or function to be evaluated at compile time. For example, you can define a constant expression like this:

constexpr int square(int x) {
    return x * x;
}

This function can be used in a constant expression context.

What about using constexpr with arrays?

Great question! You can also use constexpr with arrays. Here's an example:

constexpr int getSize() {
    return 5;
}
constexpr int myArray[getSize()] = {1, 2, 3, 4, 5};

In this case, myArray is a constant expression array.

Can constexpr be used with classes?

Yes, constexpr can be used with classes as well! You can define a constexpr constructor in a class. For example:

class Point {
public:
    constexpr Point(int x, int y) : x_(x), y_(y) {}
    int x_, y_;
};
constexpr Point p(1, 2);

This allows you to create Point objects at compile time.

Are there any limitations to using constexpr?

Yes, there are some limitations. For instance, constexpr functions cannot contain any statements that are not allowed in constant expressions, such as dynamic memory allocation or certain types of loops. It's important to ensure that the function can be evaluated at compile time.