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我的程序里边,为什么fwrite没有把数据写到文件里边啊?
- /* Copyright (C) 1991, 92, 93, 95, 96, 97 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Library General Public License as
- published by the Free Software Foundation; either version 2 of the
- License, or (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Library General Public License for more details.
- You should have received a copy of the GNU Library General Public
- License along with the GNU C Library; see the file COPYING.LIB. If not,
- write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
- #include <errno.h>;
- #include <stdio.h>;
- /* Move the file position of STREAM to OFFSET
- bytes from the beginning of the file if WHENCE
- is SEEK_SET, the end of the file is it is SEEK_END,
- or the current position if it is SEEK_CUR. */
- int
- fseek (stream, offset, whence)
- register FILE *stream;
- long int offset;
- int whence;
- {
- long int o;
- if (!__validfp (stream))
- {
- __set_errno (EINVAL);
- return EOF;
- }
- /* Write out any pending data. */
- if (stream->;__mode.__write && __flshfp (stream, EOF) == EOF)
- return EOF;
- /* Make sure we know the current offset info. */
- stream->;__offset = -1;
- if (__stdio_check_offset (stream) == EOF)
- return EOF;
- /* We are moving the file position, so we are no longer at EOF. */
- stream->;__eof = 0;
- if (stream->;__pushed_back)
- {
- /* Discard the character pushed back by ungetc. */
- stream->;__bufp = stream->;__pushback_bufp;
- stream->;__pushed_back = 0;
- }
- /* Check the WHENCE argument for validity, and process OFFSET
- into an absolute position in O. By the end of this switch,
- either we have returned, or O contains an absolute position. */
- o = offset;
- switch (whence)
- {
- default:
- __set_errno (EINVAL);
- return EOF;
- case SEEK_END:
- /* We don't know where the end of the file is,
- so seek to the position in the file the user asked
- for, and then look where that is. */
- if (stream->;__io_funcs.__seek == NULL)
- {
- __set_errno (ESPIPE);
- return EOF;
- }
- else
- {
- fpos_t pos = (fpos_t) o;
- if ((*stream->;__io_funcs.__seek)
- (stream->;__cookie, &pos, SEEK_END) < 0)
- {
- if (errno == ESPIPE)
- stream->;__io_funcs.__seek = NULL;
- return EOF;
- }
- stream->;__offset = pos;
- /* Make O be absolute, rather than
- relative to the end of the file. */
- o = pos;
- }
- /* Fall through to try an absolute seek. */
- case SEEK_SET:
- /* Make O be relative to the buffer. */
- o -= stream->;__target;
- /* Make O be relative to the current position in the buffer. */
- o -= stream->;__bufp - stream->;__buffer;
- /* Fall through to see if we can do it by
- moving the pointer around in the buffer. */
- case SEEK_CUR:
- /* If the offset is small enough, we can just
- move the pointer around in the buffer. */
- #if 0 /* Why did I think this would ever work??? */
- if (stream->;__put_limit >; stream->;__buffer)
- {
- /* We are writing. */
- if (stream->;__bufp + o >;= stream->;__buffer &&
- stream->;__put_limit >; stream->;__bufp + o &&
- stream->;__get_limit >; stream->;__bufp + o)
- {
- /* We have read all the data we will change soon.
- We can just move the pointer around. */
- stream->;__bufp += o;
- return 0;
- }
- else
- {
- /* Flush the buffer. */
- if (__flshfp(stream, EOF) == EOF)
- return EOF;
- }
- } else
- #endif
- if (o < 0 ?
- (-o <= stream->;__bufp - stream->;__buffer) :
- (o <= stream->;__get_limit - stream->;__bufp))
- {
- stream->;__bufp += o;
- return 0;
- }
- /* Turn it into an absolute seek. */
- o += stream->;__bufp - stream->;__buffer;
- o += stream->;__target;
- break;
- }
- if (o < 0)
- {
- /* Negative file position is meaningless. */
- __set_errno (EINVAL);
- return -1;
- }
- /* O is now an absolute position, the new target. */
- stream->;__target = o;
- /* Set bufp and both end pointers to the beginning of the buffer.
- The next i/o will force a call to the input/output room function. */
- stream->;__bufp
- = stream->;__get_limit = stream->;__put_limit = stream->;__buffer;
- /* Make sure __flshfp doesn't think the put_limit is at the beginning
- of the buffer because of line-buffering magic. */
- stream->;__linebuf_active = 0;
- /* If there is no seek function, seeks always fail. */
- if (stream->;__io_funcs.__seek == NULL)
- {
- /* This is preemptive, since we don't actually do the seeking.
- But it makes more sense for fseek to to fail with ESPIPE
- than for the next reading or writing operation to fail
- that way. */
- __set_errno (ESPIPE);
- return EOF;
- }
- /* Don't actually seek. The next reading or writing operation
- will force a call to the input or output room function,
- which will move to the target file position before reading or writing. */
- return 0;
- }
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