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(PHP 4 >= 4.0.4, PHP 5)

gmp_comCalculates one's complement


GMP gmp_com ( GMP $a )

Returns the one's complement of a.



Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string provided that it is possible to convert the latter to a number.

Return Values

Returns the one's complement of a, as a GMP number.


Example #1 gmp_com() example

gmp_strval($com) . "\n";

The above example will output:

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User Contributed Notes 1 note

xo at jdbartlett dot com
5 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)
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