Inserting data into file without destroying data

[Anon]

Hi,

How can I insert data into a text file without destroying the existing data?
I am building a small messageboard, and I want the newest postings to appear at the top (currently they're at the bottom)

I am using
$file = fopen("$filename", "r+");
fputs($file,"<center><hr width=\"100%\"></center>\n");
fputs($file,"<table border=\"0\">\n");
$r = date("D d/m/y (H:i)",mktime());
fputs($file,"<tr><td><font face=\"verdana, helvetice\" size=2>$name (<a href=\"mailto:$email\">$email</a>) - $r </font></td></tr>\n");
fputs($file,"<tr><td><font face=\"verdana, helvetice\" size=2>subject: $subject</font></td></tr>\n");
fputs($file,"<tr><td valign=\"top\"><font face=\"verdana, helvetice\" size=2>".htmlentities($message)."</font></td></tr>\n");
fputs($file,"</table>\n\n");
fclose($file);

the r+ doesn't work and neither does 'w'. The newest data is on top, but it destroys all messages below....

Could you please help me out here?

Bas van der Veen
webmaster www.renault-tuning.com

[Anon]

Hi Bas,

Your problem is that if you just write to the file, all data will be lost. There just is NO other way (if somebody says there IS, please tell me!) than doing this:

1.) Read all data from the file into an array or string or so.
2.) Write the new message to the file destroying all other messages.
3.) Append that new message with the older ones you've saved in step one.

I hope this helps a little.

Greetz,

Vincent Driessen
Webmaster PHP Freakz.com
http://www.phpfreakz.com/
E-mail: [e-mail]

[Anon]

Well, actually, there are a couple of ways of doing it in a file-based system.

The method Vincent described can be seen in action here:

http://yelvington.com/revannotate.php3

... where I rewrite the .comment file every time a message is entered.

The other way of doing -- which is somewhat harder -- it is to simply append the new messages to the tail of the file, but display the messages in reverse order when reading.

To do that, you'll need to store the messages in some sort of delimited/parseable format. Read the file into an array by looking for the delimiters, then walk the array in reverse order to output the messages.

[Anon]

Hi there,

I tried method number one, and after much toil, it wasn't working. So I'd like to take a shot at the reverse array.. however, you were rather vague, so I'm not quite sure what to do. My delimited file looks like this:

item1:item2:item3
item1:item2:item3
item1:item2:item3
item1:item2:item3
item1:item2:item3
item1:item2:item3

If you could just outright tell me how to read from that file in reverse and then print it (in that order), I'd be ecstatic.

[Anon]

Well, this is one of those applications where a database would be a better design choice (been there, done that!) ... but here is a quick example of how to read a data file and process it backwards.

First, let's imagine that you have a data file imaginatively named "datafile" and containing these lines:

1:first entry:more stuff
2:second entry:more stuff
3:third entry:more stuff

Now apply this code:

<?

function myfunc($item)
{
// this is where you would
// write code to parse your
// delimited file ... but we
// will just ...

    echo " $item <BR>";

    }

// read the data file into an array
$myfile = file("datafile");

// turn the whole array upside down
$myfile = array_reverse($myfile);

// walk it, applying myfunc
array_walk($myfile, 'myfunc');

?>

When you run this code against datafile, you will get something like this:

3:third entry:more stuff
2:second entry:more stuff
1:first entry:more stuff

... which is what you're looking for.

Of course, you need to rewrite myfunc() so that it actually does something useful instead of just echoing the line.