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HP-UX Reference Volume 4 of 5 > f
fread(3S) |
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NAMEfread(), fwrite() — buffered binary input/output to a stream file SYNOPSIS#include <stdio.h> size_t fread(void *ptr, size_t size, size_t nitems, FILE *stream); size_t fwrite(const void *ptr, size_t size, size_t nitems, FILE *stream); DESCRIPTIONfread() copies, into an array pointed to by ptr, up to nitems items of data from the named input stream, where an item of data is a sequence of bytes (not necessarily terminated by a null byte) of length size. fread() stops appending bytes if an end-of-file or error condition is encountered while reading stream, or if nitems items have been read. fread() leaves the file pointer in stream, if defined, pointing to the byte following the last byte read if there is one. fread() does not change the contents of stream. fwrite() appends at most nitems items of data from the array pointed to by ptr to the named output stream. fwrite() stops appending when it has appended nitems items of data or if an error condition is encountered on stream. fwrite() does not change the contents of the array pointed to by ptr. The argument size is typically sizeof(*ptr) where the pseudo-function sizeof specifies the length of an item pointed to by ptr. APPLICATION USAGEfread() and fwrite() are thread-safe. These interfaces are not async-cancel-safe. A cancellation point may occur when a thread is executing fread() or fwrite(). RETURN VALUEfread(), fread_unlocked(), fwrite(), and fwrite_unlocked() return the number of items read or written. If size or nitems is 0, no characters are read or written and 0 is returned. The value returned will be less than nitems only if a read error or end-of-file is encountered. The ferror() or feof() functions must be used to distinguish between an error condition and an end-of-file condition. WARNINGSfread_unlocked() and fwrite_unlocked() are obsolescent interfaces supported only for compatibility with existing DCE applications. New multithreaded applications should use fread() and fwrite(). SEE ALSOread(2), write(2), fopen(3S), flockfile(3S), getc(3S), gets(3S), printf(3S), putc(3S), puts(3S), scanf(3S). |
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