The following code is taken from Advanced Unix Programming by Rochkind. It is an error routine which is to be compiled with other programs. Two external variables - sys_errlist is an array of messages that correspond to the error codes, and sys_nerr is one more than the highest defined subscript in an array. errno should be tested against sys_nerr before indexing sys_errlist. #include void syserr(char *msg) { extern int errno, sys_nerr; extern char *sys_errlist[]; fprintf(stderr, "ERROR: %s (%d", msg, errno); if (errno > 0 && errno < sys_nerr) fprintf(stderr, ";%s)\n", sys_errlist[errno]); else fprintf(stderr, ")\n"); exit(1); } The problem is that I am getting the following error message when I try it with other programs that need the above. The program is named error.c : error.c:7: conflicting types for 'sys_errlist' /usr/include/stdio.h:554: previous declaration of 'sys_errlist' There is obviously a conflict between stdio.h and error.c. How to rectify this problem ? I have found this problemn on Red Hat Linux 7.2 when I compile with gcc. Please reply. Thank You, Raghu