>>>Fabio,
>>>
>>>Your "do not move anything" assumption is not right, it is not how the current code works. It would require moving AAAAABB, then AAAAAB, then AAAAA.
>>>
>>>There do exist other input strings that require more movement when proccessed right to left, it is a shame that you don't see this fact.
>>>
>>>But the whole underlying fallacy of moving the same character more than once in any algorithm is what makes it O(n²), which is a foolish waste of CPU time when it can be done O(n) as I've posted in the C++ code.
>>>
>>
>>Someone has the patience to explain as the thing to David works.
>>Thanks.
>
>I see the difference Fabio.
>
>In a right to left you never move a char too many, ie one that you will discard later, you move processed data
>
>In a left to right you are likely to move chars that you will discard later, you move non processed data
>
>

>Left >> right = move chars that will not necessarily be in the end result
>
>
>Right >> left = never move chars that are not in the end result
>
>eg: take * out
>
>12*4*6*89
>
>Left >> right
>move 1: 4*6*89   6 chars  where 2 not in the end result
>move 2: 6*89     4 chars  where 1 not in the end result
>move 3: 89       2 chars  where 0 not in the end result
>                ---
>                12 chars  where 3 not in the end result
>
>Right to left
>
>move 1: 89       2 chars where 0 not in the end result
>move 2: 689      3 chars where 0 not in the end result
>move 3: 4689     4 chars where 0 not in the end result
>                ---
>                 9 chars where 0 not in the end result
>

Thanks Gregory for your patience.

VFPT can easily implement a best code for CHRTRAN ( max 1 hour of works ):

if Param2Lengh=Param3Lengh => none char is removed, then use a on place trasl
   for prtReadWrite^=1 .... ++
    { if ...
         prtReadWrite^=...
     }
else => use a two pointers a Read and a Write
    prtWrite^=1
    for prtRead^=1 ++
     { if ...
        ....
        prtWrite^=
        prtWrite++
      }
    stringLen = prtWrite-prtStart