Bit-wise operation tricks

Question

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What USEFUL bitwise operator code tricks should a developer know about?

Hi,

What are some neat tricks with using bit-wise operations. I know that unless you're programming in C you won't have much encounters with operating on bit level. Nonetheless, there are some neat tricks that you can apply in even higher level languages. Here are a few that I already know.

bit mask: Can hold a collection of boolean values
XOR Swap: Swap 2 values in place without a third variable
XOR Linked List: Create a doubly linked list with each node only hold one address value

What are some others?

Actually bitmasks can be useful in any language. – Corey Sunwold Mar 30 '11 at 03:47 — Corey Sunwold, Mar 30 '11 at 03:47

score 0 · Accepted Answer · edited Nov 08 '11 at 19:36

0

find whether a number is odd or not

(number & 1)

edited Nov 08 '11 at 19:36

chown

51,908
16
134
170

answered Mar 30 '11 at 03:47

ultifinitus

1,813
2
19
32

2

Which doesn't work for one's complement :-) – paxdiablo Mar 30 '11 at 03:48
Oh who uses one's compliment =) (thank you google, I had no idea wtw) – ultifinitus Mar 30 '11 at 03:50
Actually, I don't know anyone that _uses_ it, but the standard allows for it (as well as sign/magnitude) on top of two's complement. You can simply state that `number` is unsigned and you've fixed the problem (a la the answer from david van brink). – paxdiablo Mar 30 '11 at 03:53
ahhhh nice, I'll do that now, uint32 standard enough? – ultifinitus Mar 30 '11 at 03:58

Bit-wise operation tricks

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