PHP, bitwise operations

Question

I do not understand, code

var_dump(decbin(0xFFFFFFFF), 0xFFFFFFFF);

print

string(32) "11111111111111111111111111111111" float(4294967295)

but if I get value using bitwise operations

$shift = 32;
$mask = ~((1 << (32 - $shift)) - 1);
var_dump(decbin($mask), $mask)

given

string(32) "11111111111111111111111111111111" int(-1)

How I can get 4294967295 ?

Community · Accepted Answer · 2023-11-17 20:38:18Z

1

PHP does not support unsigned integers, and its likely that you have a signed 32bit integer, which is -1 for all bits set.

However, you may be able to print it out anyway using printf('%u')

CommunityBot

11 silver badge

answered Mar 5, 2014 at 7:40

Daniel

4,58716 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1