>>>>> Moritz Lennert <[EMAIL PROTECTED]> writes:
[...]
>>> int D_color_number_to_RGB(int color, int &r, int &g, int &b)
[...]
>>> if (color <= 0) return 0;
>> BTW, is it a GRASS convention to use 0 to indicate failure?
>> Standard C library functions tend to use -1 for failure, while using
>> non-negative values to indicate success.
> The SUBMITTING file in the source code says:
> 8. Exit status is defined as EXIT_SUCCESS or EXIT_FAILURE, e.g.
> {
> ...
> if (G_parser (argc, argv))
> exit (EXIT_FAILURE);
> ...
> exit (EXIT_SUCCESS);
> }
> AFAIU, these are defined in stlib as being respectively 0 and 1.
Yes. But the conventions for the exit code of a program are
hardly applicable to the return value of a function.
Consider, e. g. (from ``The GNU C Library Reference Manual''):
--cut: (libc) Opening and Closing Files--
-- Function: int open (const char *FILENAME, int FLAGS[, mode_t MODE])
[...]
The normal return value from `open' is a non-negative integer file
descriptor. In the case of an error, a value of -1 is returned
instead. [...]
--cut: (libc) Opening and Closing Files--
Note that there's useful, and always non-negative, value to be
returned on success. Negative values are therefore reserved for
errors (from the point of view of the application programmer;
the only value which may actually be returned by the function in
the case of error is `-1'.)
--cut: (libc) Process Group Functions--
-- Function: int setpgid (pid_t PID, pid_t PGID)
[...]
If the operation is successful, `setpgid' returns zero. Otherwise
it returns `-1'. [...]
--cut: (libc) Process Group Functions--
And there is no such a value, so zero is used to indicate
success. Negative values are again reserved for errors.
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