what does the declaration is a definition in c++ ?

[mjhl7148]

source : https://cppreference.com/cpp/language/definition

i tried reading the whole page still does not understand i am new to c++

does it mean anything declared as constexpr must have a value like

constexpr int data = here it must have some kind of value like 75 or 45

[2kaud]

Hi. If you are new to C++ I'd suggest that you're better off learning C++ from a book or other learning resources. Have a look at https://www.learncpp.com/. cppreference isn't really designed as a teaching aid.

However, simply, constexpr means that it can be evaluated at compile time rather than run-time. So yes, it must take a value and that value must be able to be evaluated at compile time. The value once evaluated cannot be changed. It's designed to speed up run-time by doing evaluations where possible at compile time (giving a slower compile) rather than run-time.


https://www.geeksforgeeks.org/cpp/un...cifier-in-cpp/
https://stackoverflow.com/questions/...expr-and-const
https://www.cppstories.com/2022/const-options-cpp20/