Elmar Naude Elmar Naude - 1 month ago 8
PHP Question

PHP substr of hex

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?

Answer

Please read on bitwise operators.

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

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