PHP: gmp_com - Manual (original) (raw)

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_com — Calculates one's complement

Found A Problem?

xo at jdbartlett dot com ¶

15 years ago

If you're using one's compliment (bitwise NOT) to flip all $a's bits, don't forget that you need to use a mask to specify how many bits you expect in your result:

<?php gmp_and(gmp_com('1234'), '2047') ?>
>> 813 // 01100101101 in binary

I chose 2047 because 1234 is an 11-bit binary number and 2047 is the maximum an 11-bit register can hold:

11111111111  (2047)
10011010010  (1234)
01100101101  (813)