What are some practical use cases for C++20's constexpr?

What are some practical use cases for C++20's constexpr?

C++20's constexpr allows for more computations at compile time. Use cases include constant expressions, template metaprogramming, and improved performance in algorithms.

Can you give an example of a constexpr function?

Sure! Here's a simple example:

constexpr int factorial(int n) {
    return n <= 1 ? 1 : n * factorial(n - 1);
}

This function computes the factorial of a number at compile time.

How does constexpr improve performance?

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

Are there any limitations to using constexpr?

Yes, constexpr functions must adhere to certain rules, like only using a limited set of operations and types. They can't contain dynamic memory allocation or I/O operations.

What are some common mistakes when using constexpr?

Common mistakes include trying to use non-constant expressions, forgetting to mark functions as constexpr, or using unsupported operations.