เปรียบเทียบค่าใน Array function : in_array(value, array)

$value_chk = "A";
$array_chk = array("A","B","C","D");

if(in_array($value_chk, $array_chk)) {
echo "$array_chk have $value_chk";
}

else {
echo "$array_chk havn’t $value_chk";
}