<?php
$as_number = 0342352;
$as_string = "0324352";

var_dump($as_number);
var_dump($as_string);

$clean_number = filter_var($as_number, FILTER_VALIDATE_INT);
$clean_string = filter_var($as_string, FILTER_VALIDATE_INT);

var_dump($clean_number);
var_dump($clean_string);
?>

int(115946)
string(7) "0324352"
int(115946)
bool(false)