How to convert a hexadecimal value into a signed integer in PHP?

Question

I am trying to convert a hex string into a signed integer.

I am able to easily transfer it into an unsigned value with hexdec() but this does not give a signed value.

Edit:

code in VB - the two "AA" hex values are representative.

Dim bs(2) As Byte
bs(1) = "AA"
bs(2) = "AA"
Dim s As Short
s = BitConverter.ToInt16(bs, 1)

Answer 1

Check out this comment via php.net:

hexdec() returns unsigned integers. For example hexdec("FFFFFFFE") returns 4294967294, not -2. To convert to signed 32-bit integer you may do:

<?php
echo reset(unpack("l", pack("l", hexdec("FFFFFFFE"))));
?>