comedi_strerror

Description

When a Comedilib function fails, it usually returns -1 or NULL, depending on the return type. An internal library variable stores an error number, which can be retrieved with comedi_errno(). This error number can be converted to a human-readable form by the functions comedi_perror() and comedi_strerror().

These functions are intended to mimic the behavior of the standard C library functions perror(), strerror(), and errno. In particular, Comedilib functions sometimes return an error that is generated inside the C library; the comedi error message in this case is the same as the C library.

The function comedi_strerror() returns a pointer to a character string describing the Comedilib error errnum. The persistence of the returned pointer is undefined, and should not be trusted after the next Comedilib call. An unrecognized error number will return a pointer to the string "undefined error", or similar.