cerrno header

  is a C++ Standard Library. It is the C++ version of the C Standard Library errno.h header.

Variables defined by
std::errno - This variable holds an error code after certain operations fail.

Values defined by
EPERM - Permissions error ENOENT - An entry was not found ESRCH EINTR - An operation was interrupted EIO - Input/Output failure EAGAIN Note that the set of error codes is not canonical.