On Fri, Nov 08, 2019 at 03:50:43PM +0100, Tim Rühsen wrote: > > so under unusual circumstances datetime_str() can change errno. > > Sure it does - but never to 0 (Success). And that is what the OP is > reporting.
Also such things happen. Some system calls or library calls are such that all values are possible as return value, so that one cannot recognize failure from a return value like -1 or NULL. In such cases, proper behaviour is to set errno to 0, do the call, and examine errno to see whether it has become nonzero. Andries
