<?php
$c = 'A';
$isLetter = ctype_upper($c);
$isNumber = ctype_lower($c);
//isLetter is true
//isNumber is false
$symbolList = "@#$%^&*";
$c2 = '$';
$isInList = strpos($symbolList, $c2) !== false;
//isInList is true
echo "isLetter is ", var_dump($isLetter);
echo "isNumber is ", var_dump($isNumber);
echo "isInList is ", var_dump($isInList);