[Gambas-user] My quest for efficiency

[Fernando Cabral]

Thank you, Caveat [emptor?].
The code you proposed worked very, very well.
In fact, I timed it against two versions of the C program and the result
was quite good.
In C, reading from the standard input and writing to the standard output
took a trifle beyond half a second (0.6?? real time).

Meanwhile, your version in Gambas ran in 2.5?? (real time). The question
mark means little variation from trial to trial.

Out of curiosity, I wrote a Gambas version similar to the C version. Here
are the two codes:

  *Dim b As Byte*




*  While Not Eof()    b = Read As Byte    Write (b + 11) As Byte  Wend*

- - - - -  - -





*  int c;  while((c = getchar()) != EOF)             putchar(c + 11);*

The C version ran in 0.59 against the Gambas version that ran in 7.6
seconds (real time). Not too bad in my opinion!

Then I tried to stretch it a little bit and wrote:


*  Write (( Read As Byte) + 11) As Byte*
Alas! this is something Gambas does not understand.

These are just for the sake of experience. I am happy with the solution
Caveat proposed.
Thank you.

2017-07-15 17:28 GMT-03:00 Caveat <Gambas at ...3670...>:

> Something is horribly wrong, or you're running on a 286 :-)
>
> I just tested here, and the program runs on a 51 MB test file in about 5
> seconds.
>
> Some reasonably well commented code for you...
>
> Public Sub Main()
>
>   Dim inFile, outFile As File
>   Dim buff As New Byte[1024]
>   Dim idx, remBytes, readSize As Integer
>
>   ' CHANGE THIS to your input file
>   inFile = Open "/home/caveat/Downloads/mytestfile" For Read
>
>   ' CHANGE THIS to your output file
>   outFile = Open "/home/caveat/Downloads/mytestfile.out2" For Create
>
>   ' Remaining bytes starts as the total length of the file
>   remBytes = Lof(inFile)
>
>   ' Until we reach the end of the input file...guess you could instead
> check on remBytes...
>   While Not Eof(inFile)
>     If remBytes > buff.length Then
>       ' Limit reading to the size of our buffer (the Byte[])
>       readSize = buff.length
>     Else
>       ' Only read the bytes we have left into our buffer (the Byte[])
>       readSize = remBytes
>     Endif
>     ' Read from the input file into our buffer, starting at offset 0 in
> the buffer
>     buff.Read(inFile, 0, readSize)
>     ' Update the number of bytes remaining...
>     remBytes = remBytes - readSize
>     ' Run round each byte in our buffer
>     For idx = 0 To buff.length - 1
>       ' Dunno if you need any conditions, I check for > 30 as I can put
> newlines in the file to make it more readable for testing
>       If buff[idx] > 30 Then
>         ' This is the 'trick' you need to apply... subtract 11 from every
> byte in the file
>         ' Not sure how you deal with edge cases... if you have a byte of
> 5, is your result then 250?
>         buff[idx] = buff[idx] - 11
>       Endif
>     Next
>     ' Write the whole buffer out to the output file
>     buff.Write(outFile, 0, readSize)
>   Wend
>
>   Close #inFile
>   Close #outFile
>
> End
>
>
> Kind regards,
> Caveat
>
> On 15-07-17 21:24, Benoît Minisini via Gambas-user wrote:
>
>> Le 15/07/2017 à 20:49, Tony Morehen a écrit :
>>
>>> Did you try Benoit's suggestion:
>>>
>>> Public Sub Main()
>>>
>>>    Dim sIn as String
>>>    Dim sOut as String
>>>
>>>    sIn = File.Load("/home/fernando/temp/deah001.dhn")
>>>    sOut = Add11(sIn)
>>>    File.Save("/home/fernando/temp/deah001.11Added.dhn", sOut)
>>>
>>> End
>>>
>>> Public Sub Add11(InputString as String) as String
>>>    Dim bArray As Byte[]
>>>    Dim String11 As String
>>>    Dim i As Integer
>>>
>>>    bArray = Byte[].FromString(InputString)
>>>    For i = 0 To bArray.Max
>>>      bArray[i] += 11
>>>    Next
>>>   Return bArray.ToString
>>> End
>>>
>>>
>>>
>> Just a remark:
>>
>> You don't have to use Byte[].FromString.
>>
>> You can use the Bute[].Read() method instead, to load the file directly
>> into the array. You save an intermediate string that way.
>>
>> Regards,
>>
>>
>
>
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-- 
Fernando Cabral
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