freopen stdout and console

问题:

Given the following function:

freopen("file.txt","w",stdout);

Redirects stdout into a file, how do I make it so stdout redirects back into the console?

I will note, yes there are other questions similar to this, but they are about linux/posix. I'm using windows.

You can't assigned to stdout, which nullifies one set of solutions that rely on it. dup and dup2() are not native to windows, nullifying the other set. As said, posix functions don't apply (unless you count fdopen()).

回答1:

You should be able to use _dup to do this

Something like this should work (or you may prefer the example listed in the _dup documentation):

#include <io.h>
#include <stdio.h>

...
{
    int stdout_dupfd;
    FILE *temp_out;

    /* duplicate stdout */
    stdout_dupfd = _dup(1);

    temp_out = fopen("file.txt", "w");

    /* replace stdout with our output fd */
    _dup2(_fileno(temp_out), 1);
    /* output something... */
    printf("Woot!\n");
    /* flush output so it goes to our file */
    fflush(stdout);
    fclose(temp_out);
    /* Now restore stdout */
    _dup2(stdout_dupfd, 1);
    _close(stdout_dupfd);
}

回答2:

An alternate solution is:

freopen("CON","w",stdout);

Per wikipedia "CON" is a special keyword which refers to the console.

回答3:

After posting the answer I have noticed that this is a Windows-specific question. The below still might be useful in the context of the question to other people. Windows also provides _fdopen, so mayble simply changing 0 to a proper HANDLE would modify this Linux solution to Windows.

stdout = fdopen(0, "w")

#include <stdio.h>
#include <stdlib.h>
int main()
{
    freopen("file.txt","w",stdout);
    printf("dupa1");
    fclose(stdout);
    stdout = fdopen(0, "w");
    printf("dupa2");
    return 0;
}