File read, write, append

$message='';

$f=fopen('data.txt',"r");
$data=fread($f,filesize('data.txt'));
fclose($f);

$message.=$data;


$f1=fopen('data1.txt',"r");
$data1=fread($f1,filesize('data1.txt'));
fclose($f1);

$message.=$data1;


$message.='';

$f2=fopen('final.txt',"w");
fwrite($f2,$message);
fclose($f2);


function append_file($filename,$newdata) {
$f=fopen($filename,"a");
fwrite($f,$newdata);
fclose($f);
}