Question

What translation occurs when writing to a file that was opened in text mode that does not occur in binary mode? Specifically in MS Visual C.

unsigned char buffer[256]; for (int i = 0; i < 256; i++) buffer[i]=i; int size  = 1; int count = 256; 

Binary mode:

FILE *fp_binary = fopen(filename, 'wb'); fwrite(buffer, size, count, fp_binary); 

Versus text mode:

FILE *fp_text = fopen(filename, 'wt'); fwrite(buffer, size, count, fp_text); 

Answer 1

I believe that most platforms will ignore the ‘t’ option or the ‘text-mode’ option when dealing with streams. On windows, however, this is not the case. If you take a look at the description of the fopen() function at: MSDN, you will see that specifying the ‘t’ option will have the following effect:

• line feeds (‘\n’) will be translated to ‘\r\n’ sequences on output
• carriage return/line feed sequences will be translated to line feeds on input.
• If the file is opened in append mode, the end of the file will be examined for a ctrl-z character (character 26) and that character removed, if possible. It will also interpret the presence of that character as being the end of file. This is an unfortunate holdover from the days of CPM (something about the sins of the parents being visited upon their children up to the 3rd or 4th generation). Contrary to previously stated opinion, the ctrl-z character will not be appended.