Question

I’m using freopen for a GUI application using my shared library such that I can redirect debug msgs from stdout to a file

I have been using code based on a snippet from the C++ reference site:

/* freopen example: redirecting stdout */
#include <stdio.h>

int main ()
{
  freopen ("myfile.txt","w",stdout);
  printf ("This sentence is redirected to a file.");
  fclose (stdout);
  return 0;
}

This redirects stdout to myfile.txt and finally closes stdout

Is there a way to redirect to a file then effectively remove the redirection such that stdout then prints to screen as usual rather than closing it with fclose?

Answer 1

No, not in pure C. If you can assume a specific system (e.g. POSIX) there probably are options.

But frankly, freopen is IMO a hack, only needed to be compatible with prewritten code. If you’re writing new code you should instead pass the FILE * to the relevant functions and use fprintf instead of printf.