Devo aprire un file txt e sostituire le & ivi presenti con dei segni -

[andr3a]

$file = 'fileditesto.txt';
$size = filesize($file);
if($size > 0 && ($fp = fopen($file, 'r+'))) {
	$content = fread($fp, filesize($file));
	rewind($fp);
	fwrite($fp, str_replace('&', '-', $content));
	fclose($fp);
	$output = '&result=ok';
}
else
	$output = '&result=error';
echo $output;

oppure

$file = 'fileditesto.txt';
$size = filesize($file);
if($size > 0 && ($content = file_get_contents($file)) && ($fp = fopen($file, 'w'))) {
	fwrite($fp, str_replace('&', '-', $content));
	fclose($fp);
	$output = '&result=ok';
}
else
	$output = '&result=error';
echo $output;