From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 84FA5384781D for ; Tue, 11 May 2021 13:42:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 84FA5384781D Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-505-mWr_o5-TMa6hO9epcJ9S6A-1; Tue, 11 May 2021 09:42:21 -0400 X-MC-Unique: mWr_o5-TMa6hO9epcJ9S6A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 94A361034B20; Tue, 11 May 2021 13:42:20 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C39D013470; Tue, 11 May 2021 13:42:19 +0000 (UTC) From: Florian Weimer To: Peng Yu via Libc-help Subject: Re: EOF is a misnomer? References: Date: Tue, 11 May 2021 15:42:47 +0200 In-Reply-To: (Peng Yu via Libc-help's message of "Tue, 11 May 2021 08:27:46 -0500") Message-ID: <87bl9h1j54.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-help@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-help mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 May 2021 13:42:24 -0000 * Peng Yu via Libc-help: > man getchar says > > " fgetc(), getc(), and getchar() return the character read as an unsigned > char cast to an int or EOF on end of file or error." > > EOF literally stands for end of file. But the above functions can > return EOF when there is an error. > > In feof(), "eof" just means end of file as shown in man feof. > > The function feof() tests the end-of-file indicator for the stream > pointed to by stream, returning nonzero if it is set. The end-of-file > indicator can be cleared only by the function clearer(). > > So the macro name EOF is a misnomer. It could have been named as > something like EOF_OR_ERR? The fact that its name is EOF is due to > some historical reasons? Thanks. It's this way for historical reasons. EOF can also be a valid character (if sizeof (int) is 1, as permitted by the C standard), so the whole interface is a bit questionable. Thanks, Florian