What are the differences between constexpr and const in C++?

What are the differences between constexpr and const in C++?

In C++, const defines a constant variable whose value cannot be changed after initialization, while constexpr indicates that the value can be evaluated at compile time. This means constexpr can be used in contexts where compile-time evaluation is required.

Can you give me an example of when to use constexpr?

Sure! You can use constexpr for functions that can be evaluated at compile time, like calculating the factorial of a number. This allows for optimizations and can lead to faster code.

Are there any limitations to using constexpr?

Yes, constexpr functions must have a return type and contain only a single return statement or a set of statements that can be evaluated at compile time. They cannot contain dynamic memory allocation or certain types of loops.

What are some best practices for using const and constexpr?

Best practices include using const for variables that should not change and constexpr for values that can be computed at compile time. This helps improve performance and code clarity.