Tell me I'm not crazy

[Tereza Snyder]

You CAN compare arrays for equality (see the docs for "="), but evidently not for INequality!


On Sep 19, 2011, at 3:42 PM, Andre Garzia wrote:

> Tereza,
> 
> I don't think you can compare arrays like that... I never tried to do so, I
> always sort the keys and iterate thru them.
> 
> andre
> 
> On Mon, Sep 19, 2011 at 5:30 PM, Tereza Snyder <tereza at califex.com> wrote:
> 
>> I recently encountered a problem implementing an undo function in a script.
>> I needed to compare two arrays to see if any values had changed, like this:
>> 
>> put (tArray1 <> tArray2) into sDirtyFlag
>> 
>> so that sDirtyFlag would be true when the arrays failed to match. However,
>> sDirtyFlag was always false! No matter what!
>> 
>> I put the two arrays into globals and compared them in the message box,
>> like this:
>> 
>> put (gArray1 = gArray2), and the result was always correct. I thought there
>> was some hidden horrible error in my script that dementia prevented me from
>> seeing, until I realized that in my script I was using "<>" not "=" to
>> compare.
>> 
>> See if the following script, pasted into a button, mystifies you the way it
>> did me. If you comment out the line:
>> 
>> put "xx" into  tTestA2["low2"]
>> 
>> so that the arrays ARE equal you might see, as I did, that the comparison
>> is correct.
>> 
>> Evidently in LiveCode 4.5.3, buildnumber 1444, on MacOS 10.6.8,
>> 
>> "(tTestA1 <> tTestA2)" is not the same as "not(tTestA1 = tTestA2)" when the
>> arrays are unequal.
>> 
>> (I apologize that the example is so elaborate, I was attempting to
>> reproduce the error environment.)
>> 
>> 
>> tereza
>> 
>> -- mind the linewraps
>> ------------------------------
>> 
>> on mouseUp
>>   DoArrayComparison
>> end mouseUp
>> 
>> on DoArrayComparison
>>   -- create 1 array
>>   repeat for each item iii in "low1,low2,low3"
>>       repeat for each item ii in "lower1,lower2,lower3"
>>           repeat for each item i in "lowest1,lowest2,lowest3"
>>               put "data" && iii && ii && i into tA1[iii][ii][i]
>>           end repeat
>>       end repeat
>>   end repeat
>>   -- create 2 arrays from it
>>   put tA1 into tTestA1
>>   put tTestA1 into tTestA2
>>   -- make them unequal
>>   put "xx" into  tTestA2["low2"]
>>   -- do three comparisons
>>   put "(tTestA1 = tTestA2)="& (tTestA1 = tTestA2) &cr& \
>>           "(tTestA1 <> tTestA2)="& (tTestA1 <> tTestA2)  &cr& \
>>           "not(tTestA1 = tTestA2)="& not(tTestA1 = tTestA2)
>> end DoArrayComparison
>> 
>> -------------------------------
>> 
>> --
>> Tereza Snyder
>> Califex Software, Inc.
>> <www.califexsoftware.com>
>> 
>> 
>> 
>> 
>> _______________________________________________
>> use-livecode mailing list
>> use-livecode at lists.runrev.com
>> Please visit this url to subscribe, unsubscribe and manage your
>> subscription preferences:
>> http://lists.runrev.com/mailman/listinfo/use-livecode
>> 
> 
> 
> 
> -- 
> http://www.andregarzia.com All We Do Is Code.
> _______________________________________________
> use-livecode mailing list
> use-livecode at lists.runrev.com
> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:
> http://lists.runrev.com/mailman/listinfo/use-livecode