Constant Expressions: constexpr
Explore how to use constexpr in C++ to define constant expressions that are evaluated at compile time. Understand the rules for constexpr variables, functions, and user-defined types, and discover the advantages of pure functions and compile-time computation for safer, more efficient code.
Constant expressions
With constexpr, we can define an expression that can be evaluated at compile time. constexpr can be used for variables, functions, and user-defined types. An expression that is evaluated at compile time has a lot of advantages.
A constant expression:
- can be evaluated at compile time
- gives the compiler deep insight into the code
- is implicitly thread-safe
- can be constructed in the read-only memory (ROM-able)
constexpr - variables and objects
If we declare a variable as constexpr, the compiler will evaluate it at compile time. This holds true not only for built-in types but also for instantiations of user-defined types. There are a few serious restrictions for objects in order to evaluate them at compile time.
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