[php] How can I overwrite file contents with new content in PHP?

I tried to use fopen, but I only managed to append content to end of file. Is it possible to overwrite all contents with new content in PHP?

$fname = "database.php";
$fhandle = fopen($fname,"r");
$content = fread($fhandle,filesize($fname));
$content = str_replace("192.168.1.198", "localhost", $content);

$fhandle = fopen($fname,"w");
fwrite($fhandle,$content);
fclose($fhandle);

MY PREFERRED METHOD is using fopen,fwrite and fclose [it will cost less CPU]

$f=fopen('myfile.txt','w');
fwrite($f,'new content');
fclose($f);

Warning for those using file_put_contents

It'll affect a lot in performance, for example [on the same class/situation] file_get_contents too: if you have a BIG FILE, it'll read the whole content in one shot and that operation could take a long waiting time