php read big file line by line

$handle = fopen("inputfile.txt", "r");
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        // process the line read.
    }

    fclose($handle);
} else {
    // error opening the file.
} 

if ($file = fopen("file.txt", "r")) {
    while(!feof($file)) {
        $line = fgets($file);
        # do same stuff with the $line
    }
    fclose($file);
}