1234567890
abcdefghijklmn
hallo

<?php
$filename = '1.txt';

//READ FILE
$fd = fopen($filename, "r");
$jst = fread($fd, filesize($filename));
fclose($fd);

//REPLACE hallo TO hello
$jssok = str_replace('hallo', 'hello', $jst);
//如果唔得就將str_replace改做ereg_replace

//SAVE FILE
$fpt = fopen($filename ,"w+");
fputs($fpt, $jssok);
fclose($fpt);

//expgame @ AL8 Forum
?>