Solved

Setting stdout to a file.

Posted on 1997-07-09
1
358 Views
Last Modified: 2008-03-06
How do I set stdout to output to a file? I want to do this globally.  When I try to set stdout to point to a filePtr in a function the compiler gives me an error.  Thanks for your help.
0
Comment
Question by:hansmann
1 Comment
 
LVL 3

Accepted Solution

by:
LucHoltkamp earned 100 total points
Comment Utility
Try this:

#include <stdio.h>
FILE *freopen(const char *filename, const char *mode, FILE *stream);

Description

Associates a new file with an open stream.
freopen substitutes the named file in place of the open stream. It closes stream regardless of whether the open succeeds. freopen is useful for changing the file attached to stdin, stdout, or stderr.
The mode string used in calls to fopen is one of the following values:

Value      Description

r      Open for reading only.
w      Create for writing. .
a      Append; open for writing at end-of-file or create for writing if the file does not exist.
r+      Open an existing file for update (reading and writing).
w+      Create a new file for update (reading and writing).
a+      Open for append; open (or create if the file does not exist) for update at the end of the file.

To specify that a given file is being opened or created in text mode append a t to the mode string (rt w+t and so on); similarly to specify binary mode append a b to the mode string (wb a+b and so on).
If a t or b is not given in the mode string the mode is governed by the global variable _fmode. If _fmode is set to O_BINARY files are opened in binary mode. If _fmode is set to O_TEXT they are opened in text mode. These O_... constants are defined in fcntl.h.

When a file is opened for update, both input and output can be done on the resulting stream; however,

output cannot be directly followed by input without an intervening fseekor rewind
      input cannot be directly followed by output without an intervening fseek, rewind, or an input that encounters end-offile

Return Value

On successful completion freopen returns the argument stream.
On error it returns NULL.

.luc.
0

Featured Post

IT, Stop Being Called Into Every Meeting

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

Join & Write a Comment

Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
This is a short and sweet, but (hopefully) to the point article. There seems to be some fundamental misunderstanding about the function prototype for the "main" function in C and C++, more specifically what type this function should return. I see so…
The goal of this video is to provide viewers with basic examples to understand and use pointers in the C programming language.
The goal of this video is to provide viewers with basic examples to understand how to use strings and some functions related to them in the C programming language.

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

8 Experts available now in Live!

Get 1:1 Help Now