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FERROR(3)             DragonFly Library Functions Manual             FERROR(3)


clearerr, clearerr_unlocked, feof, feof_unlocked, ferror, ferror_unlocked, fileno, fileno_unlocked -- check and reset stream status


Standard C Library (libc, -lc)


#include <stdio.h> void clearerr(FILE *stream); void clearerr_unlocked(FILE *stream); int feof(FILE *stream); int feof_unlocked(FILE *stream); int ferror(FILE *stream); int ferror_unlocked(FILE *stream); int fileno(FILE *stream); int fileno_unlocked(FILE *stream);


The function clearerr() clears the end-of-file and error indicators for the stream pointed to by stream. The function feof() tests the end-of-file indicator for the stream pointed to by stream, returning non-zero if it is set. The end-of-file indicator may be cleared by explicitly calling clearerr(), or as a side- effect of other operations, e.g. fseek(). The function ferror() tests the error indicator for the stream pointed to by stream, returning non-zero if it is set. The function fileno() examines the argument stream and returns its inte- ger descriptor. The clearerr_unlocked(), feof_unlocked(), ferror_unlocked(), and fileno_unlocked() functions are equivalent to clearerr(), feof(), ferror(), and fileno() respectively, except that the caller is responsi- ble for locking the stream with flockfile(3) before calling them. These functions may be used to avoid the overhead of locking the stream and to prevent races when multiple threads are operating on the same stream.


These functions should not fail and do not set the external variable errno.


open(2), fdopen(3), flockfile(3), stdio(3)


The functions clearerr(), feof(), and ferror() conform to ISO/IEC 9899:1990 (``ISO C90''). DragonFly 3.5 January 28, 2009 DragonFly 3.5

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