Le 15/07/2017 à 16:08, Fernando Cabral a écrit :
Hi
I've found a file whose text has been obfuscated by subtracting 11 from
every byte. Now I want to bring it back to regular text. To do this I have
to add 11 to each byte read from that file. Now, I have tried several ways
to do it, and they all seemed every inefficient to me. Two examples follow
*j = 0For i = 0 To Len(RawText)str &= Chr(CByte(Asc(RawText, i) + 11)) '
either this or the following'Mid(Rawtext, i, 1) = Chr(CByte(Asc(RawText, i)
+ 11))Inc jIf j = 100000 Then Print i; Now j = 0EndifNext*
In the first option (uncommented) I am building a new string byte by byte.
In the second option (commented) I am replacing each character in place.
I expected the second option to be way faster, especially because there is
no need for the string to be reallocated. Nevertheless, it showed to be a
snail.
The first option, in spite of the fact that it grows slower and slower as
the string grows, is still way faster than the second option.
To me it does not make sense. Does it for you?
Also, is there a faster way to do this?
Strings in Gambas are immutable. The second method does not act "in
place", because this syntactic sugar actually creates a new string by
concatenating the left part, the new character, and the right part.
Use a byte array instead of a string (if you are sure that you are
dealing with ASCII of course), or a string buffer (OPEN STRING syntax
see the wiki for the details)
Regards,
--
Benoît Minisini
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