function is_numeric($var){
$str = (string)$var;
$int = (int)$var;
$strstr = (string)$int ;
if($strstr==$str) return true;
else return false;
}
function check($year,$month,$day)
{
if(is_numeric($year) and is_numeric($month) )and is_numeric($ day)){
if(checkdate($ month、$ day、$ year)){
&< br> "; Month" . $day . "日は法的な日付ではありません!
";
}
}
check("1999","1","1") ;
check("2000","2 ","31");
check("1900","2","1");
check("1900.2","2","1");
check("aaa","1", "1");
?>