Description:
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I know I shouldn't call ctype_digit() with integer values but strings. However, the variable value shouldn't be set to NULL when its passed to the function, right? :-)

Reproduce code:
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<?php

$id = 394829384;
var_dump($id);
ctype_digit($id);
var_dump($id);

?>

Expected result:
----------------
int(394829384)
int(394829384)

Actual result:
--------------
int(394829384)
NULL