isalnum not declared

[Eljay Love-Jensen]

Hi Nikolai,

It looks like your old source uses old C++ (pre-ISO 14882 standard) header 
files.  It probably also does not use compliant namespaces.

Change the header files to compliant ones (e.g., #include <iostream.h> 
becomes #include <iostream>).

And add in std:: by either "std::ID"prefix in front of each standard 
namespace identifier (metasyntactically given here as "ID"), or "using 
std::ID" near the top of the source file, or just carte blanche by "using 
namespace std;" after the #include specifier block near the top of the 
source code.

You might also want to change the ".c" extension to ".cpp".

HTH,
--Eljay