### <errno.h>

The <errno.h> include file defines symbolic macro names, such as EDOM and ERANGE, for runtime errors, and a modifiable lvalue having type int called errno. It also defines the global variable _doserrno, which is determined by the error code when an operating system error occurs.

Note: If you are going to test the value of errno after library function calls, first set it to 0, because its value may not be reset during the call.

For OS/2 and Windows, the definitions of errno and _doserrno are also provided in <stdlib.h>.

<stdlib.h>
#include