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.
hexdec() will replace of any non-hexadecimal characters it encounters by 0. This way, all left zeros are ignored, but right zeros will be valued.
See also dechex().