Check whether function is declared with C preprocessor?

Question

Is it possible to tell the C preprocessor to check whether a function (not a macro) is declared? I tried the following, but it doesn\'t appear to work:

Answer 1

The preprocessor is a simple program and knows next to nothing about the underlying language. It cannot tell if a function has been declared. Even if it could, the function may be defined in another library and the symbol is resolved during linking, so the preprocessor could not help in that regard.