what is the difference between function declaration and signature?

Question

In C or C++ what is the difference between function declaration and function signature?

I know something of function declaration but function signature is totally ne

Answer 1

Also please note that top-level const and volatile on argument are not part of the signature, according to the standard. But some compilers get this wrong.

e.g.

void f(const int, const char* const);

has the same signature as

void f(int, const char*);