BitOR and BitAND... please school me on usage

[Mechaflash]

I've never understood how BitOR/BitAND/BitNOT functions work. The helpfile explanation only adds to my confusion. Can someone help break down what its use is and help me to see the brilliance of these functions? Layman's terms highly appreciated

[jchd]

Bit* operations perform exactly what they say they do: apply a basic binary operator (NOT, AND, OR, XOR) to the parameters passed, seen as 32- or 64-bit values.

Operands are not "seen" as integers, but only as a series of 32- or 64-bits. Each bit position in the result is the operator applied to corresponding bit from the inputs. Explanations found i.e. here.

[Mechaflash]

Bit* operations perform exactly what they say they do: apply a basic binary operator (NOT, AND, OR, XOR) to the parameters passed, seen as 32- or 64-bit values.

Operands are not "seen" as integers, but only as a series of 32- or 64-bits. Each bit position in the result is the operator applied to corresponding bit from the inputs. Explanations found i.e. here.

So it's like doing a If ... OR ... OR ... OR ... Then ... etc?

Edited May 15, 2012 by mechaflash213

[jchd]

No, not If, or at least not the simplest way to see it.

Read the Wikipedia page linked.

[Mechaflash]

I have... and the article is still too foggy for me to understand. I see what they are saying: it calculates the operand (and/or/etc) at the bit level (which means if it's a string it breaks them down to their bit values?)... but at my level of comprehension, I don't see its use or value.

Is there something else I should be reading into to understand the importance and use of bitwise comparisons?

I suppose I look at these things as "what does it do... how can I use it... what can I use it for". I see the "what does it do" but I don't understand the "how can I use it" thus I wouldn't know what I could use it for in any of my projects.

[Malkey]

I have found the " script by Siao very useful and educational.

[jchd]

Binary operands are 32-bit integers and nothing else. It's rumored that future versions of AutoIt will allow for 64-bit binary operation too.

What to use it for? Mostly for packing many binary values into one single parameter.

For instance define individual bits in a status or option word to have an individual meaning. Look at how lines below

; Window Extended Styles

in WindowsConstants.au3 define individual bits to denote the style of the window you want.

When you invoke GUICreate, you pass extended style parms into one parameter, by using BitOR(option1, option2, ...).

Say some function like GUICreate gets passed a Int parameter $WinParams with those options stacked together (using BitOr).

That function would have to test bits to know how to behave. It would then BitAND the particular option constant to isolate the actual bit you passed.

[Reg2Post]

Combine bitwise operations with logic gates and you have yourself what all of us are using...

computer memory

[MvGulik]

BitMask value -> Using the single bits (in a byte or bytes) as True/False flags.

So with a byte you have 8 options you can store in it. (or 32 options with a autoit int32)

(Kinda like a 1dim-array with only true/false data.)

Saves memory and/or variable names. (which ever is more important in whatever case.)

[czardas]

I think of it a bit like light switches. Let's say we have three people who switch on different lights in the house. Two of the people turn on the same light every time. Turning the same light on twice is the same as turning the light on once: the light will be on regardless of how many people hit the switch. With BitOR I can determine how many lights will be on in the house after everyone has hit their sequence of switches. The only lights which will remain off are the ones which nobody switched on.

Now compare this example with description found in the help file.

BitOR returns 0 in each bit position where all input arguments have a 0 in the corresponding

position and 1 wherever there is at least one 1-bit.

Edited May 16, 2012 by czardas

[MvGulik]

[power]----------[light]-----.
[input]----.                 |
           |                 |
           :----[switch1]----:
           |                 |
   OR      :----[switch2]----:
           |                 |
           :----[switch3]----:
           |                 |
           .----[switch4]----.


[power]----------[light]--------------------------------------------.
[input]----.                                                        |
           |                                                        |
   AND     .----[switch1]----[switch2]----[switch3]----[switch4]----.

[just bored]

[+ definitively don't like forum message edit box behavior.]

[jaberwacky]

If you have one or two bits you may perform certain bitwise operations upon them.

Not

You may apply a not operation on one bit. This flips the bit so that zero becomes one and vice versa.

For two bits your options increase to and, or, and xor.

And

To and two bits together is to say that if both bits are one and only one then the result will be one. Otherwise, if one or both bits are zero then the result will be zero. The truth table for and follows.

| 0 1
-----------
0 | 0 0
1 | 0 1

Or

To or two bits is to say that if one or both bits are one then the result is one.

| 0 1
-----------
0 | 0 1
1 | 1 1

Xor

To xor (exclusive or) two bits is to say that if one and only one bit is one then the result will be one, otherwise zero.

| 0 1
-----------
0 | 0 1
1 | 1 0

Edited May 16, 2012 by LaCastiglione

[jchd]

This is a luxury school: one student, many teachers!

[jaberwacky]

Expect a pop quiz.