Difference between `constexpr` and `const`

Question

What\'s the difference between constexpr and const?

• When can I use only one of them?
• When can I use both and how should I

Answer 1

First of all, both are qualifiers in c++. A variable declared const must be initialized and cannot be changed in the future. Hence generally a variable declared as a const will have a value even before compiling.

But, for constexpr it is a bit different.

For constexpr, you can give an expression that could be evaluated during the compilation of the program.

Obviously, the variable declared as constexper cannot be changed in the future just like const.