fwrite() question

[bachx]

So far I've only managed to get fwrite() to write the data at the end of a file. But I want it to update/replace an existing value instead, how can this be done?

[lemmin]

You have to open the file usnig append, I think. I wrote this a while ago it uses fseek to move around the pointer.

function insertInFile($file, $string, $loc)
{
$wfile = fopen($file, "r+");
if (!$wfile)
	return false;
rewind($wfile);
fseek($wfile, $loc, SEEK_SET);
$endstring = fread($wfile, (filesize($file)-$loc));
fseek($wfile, $loc, SEEK_SET);
fwrite($wfile, $string . $endstring);
fclose($wfile);
}

You will have to modify it to replace existing text.

[bachx]

Thanks. But your function doesn't replace an existing text/value, it simply appends the $string value to wherever location that I specify. That's not really what I want.

[AdRock]

This is how I have updated a text file which replaces the whole file with what you enter

 

<?
$fund = file_get_contents($myFile);
$myFile = "../includes/thermometer/testFile.txt";
$name = $_POST['fund']; // vars from form
if (!isset($_POST['fund'])) {

?>	
<form method="post" action="<?php $_SERVER['PHP_SELF']; ?>">
    <p style="margin-left:10px;">The current fund is:<br>
    <input type="text" title="Please enter the new current fund amount" name="fund" size="30" value="<? echo $fund ?>">
</form>
<?}

else {
    $fund=$_REQUEST['fund'];
?>

<form method="post" action="<?php $_SERVER['PHP_SELF']; ?>">
    <p style="margin-left:10px;">The current fund is:<br />
    <input type="text" title="Please enter the new current fund amount" name="fund" size="30" value="<? echo $fund; ?>">
</form>

<?
    $fh = fopen($myFile, 'w') or die("can't open file");
    $stringData = $name;
    fwrite($fh, $stringData);
    fclose($fh);
}
?>

[bachx]

Errrm, I don't want to replace the whole file, just a specific value.

[otuatail]

If you mean you want to overwrite the middle of the file, then you cant. Apend will append to the end of the file. Only solution is to read the entire contents make the change and write it back.

 

Desmond.

 

[lemmin]

Like I said, you will have to modify my function to make it replace text instead of insert it. In order to replace the text, all you need to know is that length of the text you are replacing, then start the "$endstring" that many characters farther. Or a very simple method, as otuatail suggested, is to just read the entire file into a buffer, modify it, and overwrite the entire file with it.