fflush(stdin) has different behavior on different OSs about medley

[johnwcowan]

There is absolutely no ISO C or Posix way to do this.

On Windows, fflush(stdin) works.

On Linux and *BSD, fpurge(stdin) works.

On Solaris, _fpurge(stdin) works: note leading underscore.

Note that this flushes only the contents of the process's own stdio buffer; it does not affect characters still living in a kernel buffer.

[masinter]

grep -r fflush'(stdin)' src inc
src/dbgtool.c:    fflush(stdin);                                            \
src/dbgtool.c:    fflush(stdin);                                \
src/dbgtool.c:        fflush(stdin);
src/testtool.c:    fflush(stdin);                                   \
src/common.c:  fflush(stdin);
src/common.c:    fflush(stdin);
src/uraid.c:      fflush(stdin);
src/uraid.c:          fflush(stdin);
src/uraid.c:      fflush(stdin);
src/uraid.c:      fflush(stdin);

so not so important; not clear to me what bad thing will happen if fflush(stdin) doesn't do anything.

[johnwcowan]

fflush(outport) writes out the stdio buffer. fflush(inport) *discards* the data in the stdio buffer, losing it forever. I have no idea why you'd want to do this.

…

On Thu, Dec 2, 2021 at 2:31 PM Larry Masinter ***@***.***> wrote: grep -r fflush'(stdin)' src inc src/dbgtool.c: fflush(stdin); \ src/dbgtool.c: fflush(stdin); \ src/dbgtool.c: fflush(stdin); src/testtool.c: fflush(stdin); \ src/common.c: fflush(stdin); src/common.c: fflush(stdin); src/uraid.c: fflush(stdin); src/uraid.c: fflush(stdin); src/uraid.c: fflush(stdin); src/uraid.c: fflush(stdin); so not so important; not clear to me what bad thing will happen if fflush(stdin) doesn't do anything. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#22 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AANPPBXQESGTU2ZCF4XRVHTUO7CS7ANCNFSM4QOKNQRQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[nbriggs]

... because it's about to drop into its internal debugger and read input that the user was not expecting, so it wants to flush the input buffer and ensure that it is not reading typeahead.