How to declare inline functions explicitly?

Question

We don't need to declare inline functions explicitly since their implementations are defined in a header file. But for organization purpose, I want to do it. For example

// Group declaration firstly for readability.
inline void fooA();
inline void fooB();
inline void fooC();
...

// Implementations
inline void fooA()
{
   ...
}

inline void fooB()
{
   ...
}

inline void fooC()
{
   ...
}

My question is: may I need both inline keywords in declaration and implementation or one of them can be deleted?

I found an answer there Forward declaration of inline functions . So this is a repeated question. Sorry about that.

Answer 1

You need to include it in either the declaration, the definition, or both.

But note that the definition must be visible in every compilation unit that uses the function.

Answer 2

You don't need both. You can delete inline keyword in implementation and keep inline keyword when you declare functions... It is same as virtual keyword