form post action into php var - php

Question

Im in this page: website.php?page=5 and in this page I have this form:
<form method="POST" action="website.php?page=<?php echo $pagenumber; ?>">
<input type="text" name="goto" />
<input type="submit" name="submit" value="goto" />
</form>
If I write something like 3 into the text field and press the goto button (if isset.... my php code get the number and upload into the $pagenumber var)
But the new page isn't the website.php?page=3 what I want. The new page is website.php?page= (there is no number) .and if I press again then goes it to the right page.
I think in the first press when i do the $pagenumber isn't declared. Only when i press second.
How can I fix it? I must use this way i cant use session, cookie etc.
<?php if(isset($_POST['submit']))
{
$kitkeresek = $_POST['goto'];
$becsuletemw = "SELECT * FROM adatok WHERE nev = '$kitkeresek'";
$becsuletem2w = mysql_query($becsuletemw);
while( $becsuletem3w = mysql_fetch_array($becsuletem2w))
$becsuletemw = $becsuletem3w["becsulet"];
$valllamiw = mysql_query("SELECT becsulet FROM adatok WHERE becsulet > '$becsuletemw' ");
$rowsw = mysql_num_rows( $valllamiw );
$kitkeresekw = $rowsw + 1 ;
$intvizsgalat= $kitkeresekw/10;
if (is_int($intvizsgalat))
{ $pagenumber = $intvizsgalat - 1 ; }
else
{$pagenumber = floor($kitkeresekw/10); } ;
}
?>

Answer 1

When you do this :
$intvizsgalat= $kitkeresekw/10;
$intvizsgalat is float, even if the result is int, because it is the result of a division.
You can try var_dump($intvizsgalat) to confirm
try something like this:
$floatParts = $intvizsgalat - floor(intvizsgalat);
if ($floatParts == 0) {
//
} else {
//
}