CheckVariableExists.c
#ifdef CHECK_VARIABLE_EXISTS
extern int CHECK_VARIABLE_EXISTS;
#ifdef __CLASSIC_C__
int main()
{
int ac;
char* av[];
#else
int main(int ac, char* av[])
{
#endif
if (ac > 1000) {
return *av[0];
}
return CHECK_VARIABLE_EXISTS;
}
#else /* CHECK_VARIABLE_EXISTS */
#error "CHECK_VARIABLE_EXISTS has to specify the variable"
#endif /* CHECK_VARIABLE_EXISTS */