- 论坛徽章:
- 0
|
求助:一个函数输出到磁盘文件。如何将它的输出直接写到内存里?
原帖由 "fdlj53u" 发表:
试试这个方法:
#include "stdio.h"
main()
{
FILE *f1;
char buff[1024];
f1=fopen("aaa","w"
setbuf(f1,buff);
fprintf(f1,"abcdefghijklmnopqrstuvwxyZ fdlj53u..."
printf("%s\n",buff);
fclose(f1);
}
关键是 setbuf(); 重新指定文件的缓冲区。
在我的电脑上这个程序buff 中可以得到你需要的结果。 以下是setbuf 函数的man 页
SETBUF(3S) (C Programming Language Utilities) SETBUF(3S)
NAME
setbuf, setvbuf - assign buffering to a stream
SYNOPSIS
#include <stdio.h>;
void setbuf (stream, buf)
FILE *stream;
char *buf;
int setvbuf (stream, buf, type, size)
FILE *stream;
char *buf;
int type, size;
DESCRIPTION
setbuf may be used after a stream has been opened but before
it is read or written. It causes the array pointed to by
buf to be used instead of an automatically allocated buffer.
If buf is the NULL pointer input/output will be completely
unbuffered.
A constant BUFSIZ, defined in the <stdio.h>; header file,
tells how big an array is needed:
char buf[BUFSIZ];
setvbuf may be used after a stream has been opened but
before it is read or written. type determines how stream
will be buffered. Legal values for type (defined in
stdio.h) are:
_IOFBF causes input/output to be fully buffered.
_IOLBF causes output to be line buffered; the buffer will
be flushed when a newline is written, the buffer is
full, or input is requested.
_IONBF causes input/output to be completely unbuffered.
If buf is not the NULL pointer, the array it points to will
be used for buffering, instead of an automatically allocated
buffer. size specifies the size of the buffer to be used.
The constant BUFSIZ in <stdio.h>; is suggested as a good
buffer size. If input/output is unbuffered, buf and size
are ignored.
By default, output to a terminal is line buffered and all
other input/output is fully buffered.
SEE ALSO
fopen(3S), getc(3S), malloc(3C), putc(3S), stdio(3S)
Page 1 (printed 9/22/93)
SETBUF(3S) (C Programming Language Utilities) SETBUF(3S)
DIAGNOSTICS
If an illegal value for type or size is provided, setvbuf
returns a non-zero value. Otherwise, the value returned
will be zero.
NOTES
A common source of error is allocating buffer space as an
``automatic'' variable in a code block, and then failing to
close the stream in the same block.
Page 2 (printed 9/22/93) |
|