comparing content of two fields

[Scott Morrow]

Hello Bob,
--Earlier Scott posted:
> on mouseUp
>   set the itemDelimiter to tab
>   put field "All" into tBigData -- use this to compare with field "Rural" data
>   put tBigData into tBigData2 -- we will change this data as matches are found
>   put field "Rural" into tSmallData
> --<snip>

This is why I put tBigData into a second variable tBigData2.  Repeat for each uses tBigData and we change tBigData2.  No conflict.

Scott Morrow

On Apr 28, 2011, at 10:40 AM, Bob Sneidar wrote:

> It is absolutely faster. It was explained to me some time ago why. I think it still applies, although I have not tried to test it. 
> 
> It is because the engine works directly on the memory used for the object (or something like that). The problem is, the engine parses the memory and creates a list of pointers to each chunk that you are looping by. (Someone correct me if I am wrong about this.) If you change what is in that memory at any time in the repeat loop, the pointers to the chunks you are looping by do not update with it. So if the contents of the memory shift, the pointers no longer point to what you think they do. 
> 
> In the past I often got garbage in the each variable at some point, leading me to believe that the OS did some house cleaning and the contents of the memory block was no longer valid. 
> 
> That has been my understanding, but if I am mistaken, or something has been updated in the repeat for each algorithm, I'll be happy to know it. 
> 
> Bob
> 
> 
> On Apr 28, 2011, at 10:01 AM, John Dixon wrote:
> 
>> 
>> 
>> 
>> 
>>> Be careful with repeat for each. You cannot change the content of the object or block you are repeating through. "Unexpected results" is an understatement. You need to work with a copy, making sure you don't add or remove the each element (each word, each line etc.) else you get out of sync. 
>>> 
>>> Bob
>> 
>> Using 'repeat for each' with a counter is still faster than 'repeat with'
>> 
>>  put 1 into count
>>  repeat for each line thisLine in fld 1
>>     if line count of fld 1 = whatever then doSomething
>>     add 1 to count
>>  end repeat
>> 
>> be well
>> 		 	   		  
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