Hi Ken, gcc in my installation does not see iostream.h and other files. But when this project was compiled three years ago, g++ was used. Extern C {} might solve the problem, but the project was compiled in 2000 (I have the executable file), thus I would really prefer to avoid code modifications (I am a physicist, not a programmer). cctype is supposed to see what it is using, isn't it? Could the paths be set incorrectly in my installation, based on this discussion? http://os2ports.com/pipermail/ux2bs/Week-of-Mon-20030825/001097.html http://os2ports.com/pipermail/ux2bs/Week-of-Mon-20030825/thread.html#1096 Thank you, Nikolai