}
    //if we get here, there was not a non-nine number, so return true
    return true;
}
/**
 * Converts a character to an integer
 *
 * @param char $someChar Character representation of a number
 *
 * @return int $someChar Integer representation of $someChar
 */
function CharToInt($someChar)
{
    return (int) $someChar;
}
/**
 * Converts an integer to a character
 *
 * @param int $someInt  Integer to be converted to a character
 *
 * @return char $someInt Character representation of $someInt
 */
function IntToChar($someInt)
{
    return strval($someInt);
}
echo "Result (Single Nine): " . IncrementBigNum("129129") . "\n";
echo "Result (Consecutive Nines): " . IncrementBigNum("1299") . "\n";
echo "Result (No Nines): " . IncrementBigNum("122") . "\n";
echo "Result (All Nines): " . IncrementBigNum("999") . "\n";
//gets the index of the first non 9 value from the left in the number
function GetFirstNonNine($bigNumString)
{
    $lastIndex = strlen($bigNumString) - 1;
    for ($i = $lastIndex; $i >= 0; $i--) {
        if ($bigNumString[$i] != 9) {
            return $i;
        }
    }
}
//check if every number in the big number string is a nine
function CheckForAllNines($bigNumString)
{
    $lastIndex = strlen($bigNumString) - 1;
    for ($q = $lastIndex; $q >= 0; $q--) {
        if ($bigNumString[$q] != 9) {
            return false;
        }
    }
    return true;
}
function CharToInt($someChar)
{
    return (int) $someChar;
}
function IntToChar($someInt)
{
    return strval($someInt);
}
IncrementBigNum("129129");