what is this (int) do inside ternary operator?

[bilis_money]

ok, i have had visited sitepoint.com

and along the way i got this code;
[code] // If we want more fields, then use, preupload.php?number_of_fields=20
$number_of_fields = (isset($_GET['number_of_fields'])) ? (int)($_GET['number_of_fields']) : 5;
[/code]

ok, i know that the variable $number_of_fields was assigned by an isset which is from $_GET
which has a ternary condition.

now my basic question is what is an (int) doing inside a ternary condition operator?
what an (int) purpose?

thanks in advance.

[poirot]

Type casting.

[a href=\"http://www.php.net/language.types.type-juggling#language.types.typecasting\" target=\"_blank\"]http://www.php.net/language.types.type-jug...pes.typecasting[/a]