Simulating the == operator using the bitwise operators.

I would like to know how to simulate the == operator using the bitwise &, |, ~ and ^ operators in the

set /A expression= (some expression)


Specifically, I want to simulate the if stmt condition:     if (j==4)&&(option==1)   { do something } .  But I don't know of a way in DOS to combine two conditions.  I tried:     if %j%==4&%option%==1 , but this doesn't work.  I figured that if did something like this:

set /A answer1=j&4        ::wanted to get 1 or 0 based on j and 4s equality, but doesn't work because I get 4 if they    
                                     ::are equal and I can't get zero unless j is zero.
set /A answer2=option&1::wanted the same thing to happen here, which is easier because if option is one
                                     ::then the answer2 becomes 1, but if the option isn't one it won't be zero unless option is zero

:: then I compare answer2 and answer1 based on the fact they should be 1 or 0.

if %answer1%==%answer2% { do something}
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GuruGaryConnect With a Mentor Commented:
For a solution to your initial problem, you can do:

if {%j%}=={4} if {%option%}=={1} echo Do something
Hi alphonsobasemore,

a^a is 0
i.e. if two numbers are same, XORing them would give you zero. Using not would give you desired result

Also note that if you strictly want 1 and 0, then not of not would convert a value > 1 to 1

ignore the bit about not of not ... Realized that not on DOS returns bitwise compliment and not boolean opposite ... XOR part still holds
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alphonsobasemoreAuthor Commented:
Great guys I'll try both solutions and see, which one does what I want.
alphonsobasemoreAuthor Commented:
GuruGary seems to work great!  Thats essentially all I wanted to do, but I didn't know exactly how to accomplish that in the batch file using the == operator.

So GuruGary in your own words exactly what is the trick with using the

if {%j%}=={4} if {%option%}=={1} echo Do something

statement that allows you to && (and in C++) the if stmts together?  I guess its because the anding of the conditions is the same as using nested if statements right? But whats the {} for? What if I wanted to || (or in C++) the stmts together what would I change?
alphonsobasemoreAuthor Commented:
sunnycoder I've switched to your a^a solution, because it seems I can manipulate the answers to do what I want when I need to OR the answer to j==4 with option==1.

I can't figure out a way to OR GuruGary's solution as needed!

I used this:

set /A ans="(!(j^4))|(!(option^1))"

or simply

set /A ans="(!(j^4))|option"

, which is the same as if ((j==4)||(option==1)) only I use bitwise operators to get a 1 or 0 for the final condition's value.
Sorry for the delay.  Not sure if you are even using my solution any more ... but to answer your question the statement is basically
if ((j==4) and (option==1)) then do something

or closer to the actual batch code in C format:
if (j==4) {
   if (option==1) {
      echo Do something;

The {} is to prevent errors in case you check against a blank value.  For example, if %option% never gets set, then the batch file line would be
if ==1
... which is not valid syntax and would generate an error.  If you use the {} and %option% is blank the batch code would be
if {}=={1}
which is valid syntax.  You can use most any character(s) to compare as long as they are the same on both sides.
alphonsobasemoreAuthor Commented:
Just like I thought about your code!  But if you look at the later posts that I have on this question you'll see that the code you gave isn't quite what I needed.  If you know the alternate format of that code, but instead of using an and format I wanted to use the or format of that code.  Is there a way to state if ((j==4)or(option==1)) then do something in dos?  Or  am I stuck using the code in the and format?
Well, I can think of several ways to accomplish that task, but not with a "logical OR" directly in the IF statement.  See if any of these will work for what you want to do:

Batch 1:
if {%j%}=={4} (
   echo Do something
   ) else if {%option%}=={1} echo Do something

Batch 2:
if {%j%}=={4} call :Something
if {%option%}=={1} if not {%j%}=={4} call :Something
goto :EOF

echo Do something
goto :EOF

Batch 3:
set test=0
if {%j%}=={4} set /a test+=1
if {%option%}=={1} set /a test+=1
if %test% GEQ 1 echo Do something

Batch 4:
if {%j%}=={4} (
   goto :Continue
   ) else if {%option%}=={1} goto :Continue
goto :Skip
echo Do something

... or any combinations of the ideas above.
Post back if you have questions or need more help or ideas.
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