errno -- Global Variable

External integer for return of error status
#include <errno.h>
extern int errno;

errno is an external integer that COHERENT links into each of its programs.
COHERENT sets errno  to the negative value of any  error status returned to
any function that performs COHERENT system calls.

Mathematical functions  use errno to indicate  classifications of errors on
return.   errno is  defined within  the header  file errno.h.   Because not
every  function uses  errno, it  should be polled  only in  connection with
those functions that document its use and the meaning of the various status
values.  For  the names of  the error codes  (as defined in  errno.h, their
value, and the message returned by the function perror, see errno.h.

Example

For an example  of using errno in a mathematics  program, see the entry for
acos.

See Also

errno.h,
libm,
perror(),
Programming COHERENT,
signal()
ANSI Standard, §7.1.4
POSIX Standard, §2.4

© 2012 by Stephen A. Ness