wfreopen

Name

wfreopen
- stream open function

Library

libc.lib

Synopsis

#include <wchar.h>

FILE * wfreopen (const wchar_t * path, const wchar_t * mode, FILE *stream);

Return values

Upon successful completion wfreopen, returns a FILE pointer. Otherwise, NULL is returned and the global variable errno is set to indicate the error.

Detailed description

The wfreopen function opens the file whose name is the string pointed to by path and associates the stream pointed to by stream with it. The original stream (if it exists) is closed. The mode argument is used just as in the wfopen function.

If the path argument is NULL, wfreopen attempts to re-open the file associated with stream with a new mode. The new mode must be compatible with the mode that the stream was originally opened with:

Streams originally opened with mode "r" can only be reopened with that same mode.
Streams originally opened with mode "a" can be reopened with the same mode, or mode "w."
Streams originally opened with mode "w" can be reopened with the same mode, or mode "a."
Streams originally opened with mode "r+," "w+," or "a+" can be reopened with any mode.

The primary use of the wfreopen function is to change the file associated with a standard text stream (stderr, stdin, or stdout).

Examples

/* wfreopen example: redirecting stdout */
#include <stdio.h>
#include <wchar.h>
int main ()
{
  wfreopen (L"c:\myfile.txt",L"w",stdout);
  printf ("This sentence is redirected to a file.");
  fclose (stdout);
  return 0;
}

Output:

Contents of myfile.txt:This sentence is redirected to a file.
The output here is redirected from stdout to file myfile.txt

Errors

[`EINVAL`]
	The mode argument to `wfreopen,` was invalid.

The wfreopen function may also fail and set errno for any of the errors specified for the routine wopen.

Limitations

All the limitations that apply to wfopen apply to wfreopen also.

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