Athena is not yet running a fully ANSI compliant system; there are several other header files described in the standard that do not exist. To write a program that will compile correctly on both ANSI and non-ANSI systems, put this text at the top of your .c file:
#if defined(__STDC__) && !defined(__HIGHC__) #include <stdlib.h> #endifThe symbol __STDC__ is always defined by an ANSI C compiler, and that code tells the compiler only to #include <stdlib.h> if it is defined, so it will not be included on non-ANSI systems.
The functions that are declared in stdlib.h on an ANSI system are, for the most part, available in libc.a (the library that is automatically linked with every C program).
For more information on these issues, see the stock answers on What C COMPILERS are available and What is ANSI C.