From: "Glynne Casteel" <glynnec AT ix DOT netcom DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Binary File Operations
Date: Sun, 13 Sep 1998 11:47:04 -0600
Organization: ICGNetcom
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IIibanezII wrote in message
<1998091221320200 DOT RAA14256 AT ladder01 DOT news DOT aol DOT com>...
>I have been trying to learn binary file operations by making a file that
gets a
>string as input and writes it to a binary file, and then a second program
which
>reads from a binary file. Could someone please tell me what I am doing
wrong?
>Here's the code:
>
>char string[100];
>FILE *test;
>test = fopen("test.dat", "wb");
>
>fgets(string, 1, stdin);
>fwrite(string, 1, 100, test);
>fclose(test)
>

To avoid these kinds of problems, you should use I/O functions that are
meant to be used together.
When working with binary data, use fwrite() for output and use fread() for
input.
When working with string data, use fprintf() or fputs() for output and use
fgets() for input.


Some other points to remember:

- fgets() will usually return a newline just before the null terminator,
unless the input string exceeds the maximum specified buffer length;  you'll
probably want to trim it before you work with the string.

- fread() returns a count of how much data was read; you'll want to use this
value to avoid data that was not placed in the buffer by the current read
operation.  Even though your buffer is 100 bytes long, fread() may only fill
the first 22 bytes with data, the remaining bytes are unaltered.

Glynne