有点搞不懂freopen

[tianxiaogang12]

请大侠帮我讲讲
freopen("input.txt", "r", stdin);
中的stdin的意思 且用在这有什么用 感谢

[tianxiaogang12]

还有就是 freopen("input.txt", "r", stdin);
返回的是什么 啊 虽然说是返回的file指针
但还是不太清楚啊

[nadirboxer]

stdin就是标准输入流
键盘输入

[tatbaby]

FILE *freopen(
const char *path,
const char *mode,
FILE *stream
);

Parameters
path
Path of new file.
mode
Type of access permitted.
stream
Pointer to FILE structure.
Return Value
Each of these functions returns a pointer to the newly opened file. If an error occurs, the original file is closed and the function returns a NULL pointer value.

[tatbaby]

The freopen function closes the file currently associated with stream and reassigns stream to the file specified by path.

stdin 标准输入流，接受来自键盘的输入
FILE *finfreopen("input.txt", "r", stdin);
/*输入来自文件input.txt，而非键盘输入；只读方式；*/
在这里，此句关闭了当前的键盘输入流stdin，并且将输入流重新赋值为指定的input.txt。

[hslinux]

<stdio.h>:

FILE *stdin;

FILE *stdout;

FILE *stderr;

stdin Standard input
stdout Standard output
stderr Standard error