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### Bitwise comparison of 2 numbers

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```I'm completely new to awk, so don't even know if this is possible. I
need to modify some old code so that it performs a bitwise "and" on
two numbers. Doing something like "variable = 7 AND 9" returns 79
rather than 1.

Rich
```
 0
Reply 12/4/2003 10:45:30 AM

```richdyer_2000@hotmail.com (Richard Dyer) writes:

> I'm completely new to awk, so don't even know if this is possible. I
> need to modify some old code so that it performs a bitwise "and" on
> two numbers. Doing something like "variable = 7 AND 9" returns 79
> rather than 1.

There's no built-in binary AND in standard awk, you'll have to do it
the hard way with a division loop, or call an external program.

Here's an example of a division loop ANDer (not optimized in
any way and slow as molasses, but it should work):

function binand(x,y,
z,n) {  # local variables
z = 0
n = 1
while (x >= 1 && y >= 1) {
if (x%2 == 1 && y%2 == 1) z += n
x = (x - (x%2))/2
y = (y - (y%2))/2
n *= 2
}
return z
}

--
Tapani Tarvainen
```
 0
Reply Tapani 12/4/2003 11:36:57 AM

```In article <12652ad6.0312040245.5b2221ab@posting.google.com>,
Richard Dyer <richdyer_2000@hotmail.com> wrote:
>I'm completely new to awk, so don't even know if this is possible. I
>need to modify some old code so that it performs a bitwise "and" on
>two numbers. Doing something like "variable = 7 AND 9" returns 79
>rather than 1.

you could paste two numbers together like this:

echo "3" | awk '{a=7; b=9; c=a "" b; print c}'

79

Chuck Demas

--
Eat Healthy        |   _ _   | Nothing would be done at all,
Stay Fit           |   @ @   | If a man waited to do it so well,
Die Anyway         |    v    | That no one could find fault with it.
demas@theworld.com |  \___/  | http://world.std.com/~cpd
```
 0
Reply demas 12/4/2003 11:47:19 AM

```In article <n6vfowizl2.fsf@tt.oma.it.jyu.fi>,
Tapani Tarvainen  <gn20031204T131637@tt.oma.it.jyu.fi> wrote:
>richdyer_2000@hotmail.com (Richard Dyer) writes:
>
>> I'm completely new to awk, so don't even know if this is possible. I
>> need to modify some old code so that it performs a bitwise "and" on
>> two numbers. Doing something like "variable = 7 AND 9" returns 79
>> rather than 1.
>
>There's no built-in binary AND in standard awk, you'll have to do it
>the hard way with a division loop, or call an external program.
>
>Here's an example of a division loop ANDer (not optimized in
>any way and slow as molasses, but it should work):

It looks like the OP used the phrase 'bitwise "and"' to mean that which most
of us would refer to as "string concatenation".  This operation is, BTW,
included in all versions of AWK.

Anyway, all of the usable AWK implementations (GAWk & TAWK) do have built-in
bitwise operators.
```
 0
Reply gazelle 12/4/2003 1:23:49 PM

```In article <bqn6s7\$8jc\$1@pcls3.std.com>,
Charles Demas <demas@TheWorld.com> wrote:

% you could paste two numbers together like this:
%
% echo "3" | awk '{a=7; b=9; c=a "" b; print c}'

In fact, the "" isn't needed, either. Just

c = a b

is sufficient. I wanted to point out that you need to be careful
if you want to use this in an expression without first assigning
it to another variable. Use parentheses!
a b * 7   # is 781 when a is 7 and b is 9
(a b) * 7 # is 711
--

Patrick TJ McPhee
ptjm@interlog.com
```
 0
Reply ptjm 12/4/2003 10:25:44 PM

```Patrick TJ McPhee wrote:
> In article <bqn6s7\$8jc\$1@pcls3.std.com>,
> Charles Demas <demas@TheWorld.com> wrote:
>
> % you could paste two numbers together like this:
> %
> % echo "3" | awk '{a=7; b=9; c=a "" b; print c}'
>
> In fact, the "" isn't needed, either. Just
>
>   c = a b
>
> is sufficient. I wanted to point out that you need to be careful
> if you want to use this in an expression without first assigning
> it to another variable. Use parentheses!
>   a b * 7   # is 781 when a is 7 and b is 9
>   (a b) * 7 # is 711

I hope you don't get that result.

a b * 7 -> 7 (9 * 7) -> 7 63 -> 763

and

(a b) * 7 -> (7 9) * 7 -> 79 * 7 -> 553

--
Regards,

---Robert

```
 0
Reply Robert 12/4/2003 11:50:33 PM

```In article <12652ad6.0312040245.5b2221ab@posting.google.com>,
Richard Dyer <richdyer_2000@hotmail.com> wrote:
>I'm completely new to awk, so don't even know if this is possible. I
>need to modify some old code so that it performs a bitwise "and" on
>two numbers. Doing something like "variable = 7 AND 9" returns 79
>rather than 1.

If you're using gawk:

variable = and(7,9)

Otherwise, you'll need to use a division loop to convert the values to binary.

John
--
John DuBois  spcecdt@armory.com  KC6QKZ/AE  http://www.armory.com/~spcecdt/
```
 0
Reply spcecdt 12/5/2003 12:17:12 AM

```In article <3fcfce88\$0\$1098\$8eec23a@newsreader.tycho.net>,
John DuBois <spcecdt@deeptht.armory.com> wrote:
>Richard Dyer <richdyer_2000@hotmail.com> wrote:
>>I'm completely new to awk, so don't even know if this is possible. I
>>need to modify some old code so that it performs a bitwise "and" on
>>two numbers. Doing something like "variable = 7 AND 9" returns 79
>>rather than 1.
>
>If you're using gawk:
>
>variable = and(7,9)
>
>Otherwise, you'll need to use a division loop to convert the values to binary.

See my other post in this thread.  Apparently, the OP is asking about string
concatenation, not bitwise operations.
```
 0
Reply gazelle 12/5/2003 1:19:04 AM

```In article <bqomq9\$1h2\$1@yin.interaccess.com>,
Kenny McCormack <gazelle@interaccess.com> wrote:
>John DuBois <spcecdt@deeptht.armory.com> wrote:
>>Richard Dyer <richdyer_2000@hotmail.com> wrote:
>>>I'm completely new to awk, so don't even know if this is possible. I
>>>need to modify some old code so that it performs a bitwise "and" on
>>>two numbers. Doing something like "variable = 7 AND 9" returns 79
>>>rather than 1.
>>
>>If you're using gawk:
>>
>>variable = and(7,9)
>>
>>Otherwise, you'll need to use a division loop to convert the values to binary.
>
>See my other post in this thread.  Apparently, the OP is asking about string
>concatenation, not bitwise operations.

Surprising how many people jumped at the keyword and didn't read
further to see if it applied.

Even more surprising was that two of them posted public replies.

Chuck Demas

--
Eat Healthy        |   _ _   | Nothing would be done at all,
Stay Fit           |   @ @   | If a man waited to do it so well,
Die Anyway         |    v    | That no one could find fault with it.
demas@theworld.com |  \___/  | http://world.std.com/~cpd
```
 0
Reply demas 12/5/2003 1:42:44 AM

```gazelle@yin.interaccess.com (Kenny McCormack) writes:

> >richdyer_2000@hotmail.com (Richard Dyer) writes:

> >> I need to modify some old code so that it performs a bitwise "and" on
> >> two numbers. Doing something like "variable = 7 AND 9" returns 79
> >> rather than 1.

> It looks like the OP used the phrase 'bitwise "and"' to mean
> that which most of us would refer to as "string concatenation".

Perhaps. As I read it, however, he is complaining that "something
like 7 AND 9" returns 79 (concatenation), whereas he would want 1
(bitwise AND).

Let's hope he will clarify, guessing won't do much good.

--
Tapani Tarvainen
```
 0
Reply Tapani 12/5/2003 6:17:11 AM

```Thanks to all of you for the help there.

I actually cheated in the end. I was using awk to generate a STOL
script from a text file. It eventually dawned on me that i could
therefore just get awk to print a bitwise and statement to the STOL
script and let STOL do all the maths.

Rich
```
 0
Reply richdyer_2000 12/5/2003 9:44:55 AM

```In article <dLPzb.10187\$cd.9894@news.cpqcorp.net>,
Robert Katz  <katz@hp.com> wrote:
% Patrick TJ McPhee wrote:

% >   a b * 7   # is 781 when a is 7 and b is 9
% >   (a b) * 7 # is 711
%
% I hope you don't get that result.

It is if you use a b * 9, which is what I was thinking. Just ignore what
I write and go with what I'm thinking.

--

Patrick TJ McPhee
ptjm@interlog.com
```
 0
Reply ptjm 12/5/2003 8:22:27 PM

```In article <n6r7zj94bc.fsf@tt.oma.it.jyu.fi>,
Tapani Tarvainen  <gn20031205T081246@tt.oma.it.jyu.fi> wrote:

% Perhaps. As I read it, however, he is complaining that "something
% like 7 AND 9" returns 79 (concatenation), whereas he would want 1
% (bitwise AND).

I think you're probably right. The rest of us should pay closer attention.

% Let's hope he will clarify, guessing won't do much good.

I can't agree with this. Guessing is the best thing, and much more
interesting than knowing.

--

Patrick TJ McPhee
ptjm@interlog.com
```
 0
Reply ptjm 12/5/2003 8:25:20 PM

```On 4 Dec 2003 02:45:30 -0800 in comp.lang.awk,
richdyer_2000@hotmail.com (Richard Dyer) wrote:

>I'm completely new to awk, so don't even know if this is possible. I
>need to modify some old code so that it performs a bitwise "and" on
>two numbers. Doing something like "variable = 7 AND 9" returns 79
>rather than 1.

AND is not an awk keyword, so awk assumes it is a variable and creates
it for you with the null string value "", which is then used in the
implicit concatenation "7" AND "9" resulting in "79".
You need to use awk's bitwise functions and(,), or(,), xor(,),
compl(), lshift(,), rshift(,). The statement "variable = and(7,9)"
will give you the result you are looking for.
--
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian.Inglis@CSi.com 	(Brian dot Inglis at SystematicSw dot ab dot ca)
```
 0
Reply Brian 12/6/2003 6:30:08 AM

```In article <bqomq9\$1h2\$1@yin.interaccess.com>,
Kenny McCormack <gazelle@interaccess.com> wrote:
>John DuBois <spcecdt@deeptht.armory.com> wrote:
>>Richard Dyer <richdyer_2000@hotmail.com> wrote:
>>>I'm completely new to awk, so don't even know if this is possible. I
>>>need to modify some old code so that it performs a bitwise "and" on
>>>two numbers. Doing something like "variable = 7 AND 9" returns 79
>>>rather than 1.
>>
>>If you're using gawk:
>>
>>variable = and(7,9)
>>
>>Otherwise, you'll need to use a division loop to convert the values to binary.
>
>See my other post in this thread.  Apparently, the OP is asking about string
>concatenation, not bitwise operations.

No, he was asking about bitwise operations.  He said he wanted to do a 'bitwise
and', he showed the result he gets when he tried to do this using a nonexistant
binary AND operator (string concatenation, which he didn't want), and he showed
what he did want to get in the example he gave (the result of a bitwise and).

John
--
John DuBois  spcecdt@armory.com  KC6QKZ/AE  http://www.armory.com/~spcecdt/
```
 0
Reply spcecdt 12/7/2003 2:21:48 AM

```John,

It's nice to see at least one person understands english as well as awk!

Rich
```
 0
Reply richdyer_2000 12/8/2003 1:25:12 PM

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