PHP substr of hex

Question

Is it possible to get a subsection of a hex value? For example:

0x7dd becomes 0xdd

Or even to get a subsection of binary value. For example:

$hex = 0x7dd;    
$bin = hex2bin($hex);
$ bin = substr($bin,4); //so it excludes the four most significant bits ie. the most significant hex digit

Does anybody know of a efficient way of oing this?

Possible duplicate of [How to implement a bitmask in php?](http://stackoverflow.com/questions/11880360/how-to-implement-a-bitmask-in-php) — Alessandro Da Rugna, Oct 30 '16 at 14:06

score 1 · Accepted Answer · answered Oct 30 '16 at 13:57

1

Applying & (bitwise and) on a mask, or >> (right-shift) could be what your looking for (without converting back and forth to string).

For example:

0x7dd & 0xff == 0xdd

where & 0xff essentially ignores everything except the last two hex digits

answered Oct 30 '16 at 13:57

Uri Goren

The "&" operator is what I was looking for, my encryption algorithm now works perfectly. – Elmar Naude Oct 30 '16 at 14:25

1 Answers1