Constant Expressions

With the keyword constexpr, we 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 many advantages. A constant expression does the following:

• It can be evaluated at compile time.
• It gives the compiler deep insight into the code.
• It is implicitly thread-safe.
• It can be constructed in the read-only memory (ROM-able).