Returns the decimal equivalent of the hexadecimal number represented by the hex_string argument. hexdec() converts a hexadecimal string to a decimal number. The largest number that can be converted is 7fffffff or 2147483647 in decimal. As of PHP 4.1.0, this function can also convert larger numbers. It returns float in that case.
hexdec() will ignore any non-hexadecimal characters it encounters.
See also dechex(), bindec(), octdec() and base_convert().