Someone

$filename = "counter.txt";
@$fptr = fopen($filename, "r+");

if ($fptr == NULL) {
    @$fptr = fopen($filename, "w+");
    fwrite($fptr, "1");
    fclose($fptr);
    echo "1";
}
else {
    $data = fread($fptr, filesize($filename));
    $dataInt = (int) $data;
    $dataInt++;
    rewind($fptr);
    fwrite($fptr, $dataInt);
    fclose($fptr);
    echo $dataInt;
}