Speed2

[Ing. Roberto Nisthal]

> It's extremely slow..... about 30 min to load a 350k file.
String concatenation is the culprit...
Several suggestions

1) Get the size of the file you are handling
2) Allocate enough space in a buffer, for example using the space function
3) Read the file in bigger chunks
4) DON'T USE STRING CONCATENATION, if you need a string use something like
mid$(Result,i,1) = Character

[Ing. Roberto Nisthal]

> It's extremely slow..... about 30 min to load a 350k file.
String concatenation is the culprit...
Several suggestions

1) Get the size of the file you are handling
2) Allocate enough space in a buffer, for example using the space function
3) Read the file in bigger chunks
4) DON'T USE STRING CONCATENATION, if you need a string use something like
mid$(Result,i,1) = Character

[Shawn Wilson]

Here is a challenging one....

Below is a function which will open a file and return a string representation
of the hexadecimal
contents of that file.

It's extremely slow..... about 30 min to load a 350k file.

Here comes the fun....how can I modify this function to perform in < 10 seconds
(+/- a few)
without having to get a faster computer or having to write a function in
C.

Do you think using the windows API will make things faster? If so, can someone
give me a VB function
using the windows API to do this?

I should have paid attention in my data structures and algorithm class. )

Thanks to anyone/everyone who has a way to do this.



Public Function OpenWithString() As String
Dim Character As String


Dim Variable As Byte
Dim Result As String
Dim i As Long

i = 0

Open "C:\temp\jde_docs_79.zip" For Binary Access Read As #1 ' Open file
Result = "0x"
Do While Not EOF(1)

Get #1, , Variable
Character = Hex(Variable)
If Len(Character) = 1 Then
Character = "0" & Character
End If
Result = Result & Character
Loop

' Result now holds the complete string (which is 2 times the original file
length plus 4 bytes)

Close #1

OpenWithString = Result

End Function

[Bruno Paris]

Hi, Shawn
Here is the code:

Option Explicit
Private Declare Function GetTickCount Lib "kernel32" () As Long

Private Sub Form_Click()
Dim s As String, tim As Long
tim = GetTickCount ' start timer

s = OpenWithString

Caption = (GetTickCount - tim) / 1000 ' report time
End Sub

Public Function OpenWithString() As String
Dim b() As Byte
Dim flen As Long, i As Long
Static hextable(255) As String
Static initDone As Boolean

If Not initDone Then ' do this only once
initDone = True
For i = 0 To 15
hextable(i) = "0" & Hex(i)
Next
For i = 16 To 255
hextable(i) = Hex(i)
Next
End If

' Read the file into byte array
Open "C:\temp\jde_docs_79.zip" For Binary _
Access Read Lock Read Write As #1
flen = LOF(1)
ReDim b(0 To flen - 1) As Byte
Get #1, , b()
Close #1

' prepare big string
OpenWithString = Space(2 + 2 * flen)

' fill the string (non-API method)
Mid$(OpenWithString, 1, 2) = "0x"
For i = 0 To flen - 1
Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
Next
End Function


When compiling, use advanced optimizations (remove bounds
check, remove integer overflow checks)

Regards,
Bruno


Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
>
>Here is a challenging one....
....

[Bruno Paris]

Hi, Shawn
Here is the code:

Option Explicit
Private Declare Function GetTickCount Lib "kernel32" () As Long

Private Sub Form_Click()
Dim s As String, tim As Long
tim = GetTickCount ' start timer

s = OpenWithString

Caption = (GetTickCount - tim) / 1000 ' report time
End Sub

Public Function OpenWithString() As String
Dim b() As Byte
Dim flen As Long, i As Long
Static hextable(255) As String
Static initDone As Boolean

If Not initDone Then ' do this only once
initDone = True
For i = 0 To 15
hextable(i) = "0" & Hex(i)
Next
For i = 16 To 255
hextable(i) = Hex(i)
Next
End If

' Read the file into byte array
Open "C:\temp\jde_docs_79.zip" For Binary _
Access Read Lock Read Write As #1
flen = LOF(1)
ReDim b(0 To flen - 1) As Byte
Get #1, , b()
Close #1

' prepare big string
OpenWithString = Space(2 + 2 * flen)

' fill the string (non-API method)
Mid$(OpenWithString, 1, 2) = "0x"
For i = 0 To flen - 1
Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
Next
End Function


When compiling, use advanced optimizations (remove bounds
check, remove integer overflow checks)

Regards,
Bruno


Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
>
>Here is a challenging one....
....

[Shawn Wilson]

Bruno, Roberto:

Thankyou very much for your answers. This code is code is sharp.
It would have taken me a long time to figure this out.

This code is great.....amazingly much faster than my original implementation.

Thank a lot again guys...

Are there any good data structures and algorithms books for VB that you may
know of?

Shawn


"Bruno Paris" <nospam_ameba@zg.tel.hr> wrote:
>Hi, Shawn
>Here is the code:
>
>Option Explicit
>Private Declare Function GetTickCount Lib "kernel32" () As Long
>
>Private Sub Form_Click()
> Dim s As String, tim As Long
> tim = GetTickCount ' start timer
>
> s = OpenWithString
>
> Caption = (GetTickCount - tim) / 1000 ' report time
>End Sub
>
>Public Function OpenWithString() As String
> Dim b() As Byte
> Dim flen As Long, i As Long
> Static hextable(255) As String
> Static initDone As Boolean
>
> If Not initDone Then ' do this only once
> initDone = True
> For i = 0 To 15
> hextable(i) = "0" & Hex(i)
> Next
> For i = 16 To 255
> hextable(i) = Hex(i)
> Next
> End If
>
> ' Read the file into byte array
> Open "C:\temp\jde_docs_79.zip" For Binary _
> Access Read Lock Read Write As #1
> flen = LOF(1)
> ReDim b(0 To flen - 1) As Byte
> Get #1, , b()
> Close #1
>
> ' prepare big string
> OpenWithString = Space(2 + 2 * flen)
>
> ' fill the string (non-API method)
> Mid$(OpenWithString, 1, 2) = "0x"
> For i = 0 To flen - 1
> Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
> Next
>End Function
>
>
>When compiling, use advanced optimizations (remove bounds
> check, remove integer overflow checks)
>
>Regards,
>Bruno
>
>
>Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
>>
>>Here is a challenging one....
>....
>
>

[Shawn Wilson]

Bruno, Roberto:

Thankyou very much for your answers. This code is code is sharp.
It would have taken me a long time to figure this out.

This code is great.....amazingly much faster than my original implementation.

Thank a lot again guys...

Are there any good data structures and algorithms books for VB that you may
know of?

Shawn


"Bruno Paris" <nospam_ameba@zg.tel.hr> wrote:
>Hi, Shawn
>Here is the code:
>
>Option Explicit
>Private Declare Function GetTickCount Lib "kernel32" () As Long
>
>Private Sub Form_Click()
> Dim s As String, tim As Long
> tim = GetTickCount ' start timer
>
> s = OpenWithString
>
> Caption = (GetTickCount - tim) / 1000 ' report time
>End Sub
>
>Public Function OpenWithString() As String
> Dim b() As Byte
> Dim flen As Long, i As Long
> Static hextable(255) As String
> Static initDone As Boolean
>
> If Not initDone Then ' do this only once
> initDone = True
> For i = 0 To 15
> hextable(i) = "0" & Hex(i)
> Next
> For i = 16 To 255
> hextable(i) = Hex(i)
> Next
> End If
>
> ' Read the file into byte array
> Open "C:\temp\jde_docs_79.zip" For Binary _
> Access Read Lock Read Write As #1
> flen = LOF(1)
> ReDim b(0 To flen - 1) As Byte
> Get #1, , b()
> Close #1
>
> ' prepare big string
> OpenWithString = Space(2 + 2 * flen)
>
> ' fill the string (non-API method)
> Mid$(OpenWithString, 1, 2) = "0x"
> For i = 0 To flen - 1
> Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
> Next
>End Function
>
>
>When compiling, use advanced optimizations (remove bounds
> check, remove integer overflow checks)
>
>Regards,
>Bruno
>
>
>Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
>>
>>Here is a challenging one....
>....
>
>

[Bruno Paris]

Hi, Shawn

>Bruno, Roberto:
>
>Thankyou very much for your answers.
You are welcome.

See also this article: Play VB's Strings
http://www.vb2themax.com/HtmlDoc.asp...Articles&ID=30

Regards,
Bruno

[Bruno Paris]

Hi, Shawn

>Bruno, Roberto:
>
>Thankyou very much for your answers.
You are welcome.

See also this article: Play VB's Strings
http://www.vb2themax.com/HtmlDoc.asp...Articles&ID=30

Regards,
Bruno

[Eric D. Burdo]

Rod Stephens has a good algorithms book...

http://www.amazon.com/exec/obidos/AS...2-7980153-2040
942

--

Eric D. Burdo, Red-Leif International
VB Programmer and Consultant
<http://www.redleif.com/vb>

*** Please reply to the newsgroup so all can benefit. ***


"Shawn Wilson" <wilso_s@mailcity.com> wrote in message
news:3989eb97$1@news.devx.com...
>
> Bruno, Roberto:
>
> Thankyou very much for your answers. This code is code is sharp.
> It would have taken me a long time to figure this out.
>
> This code is great.....amazingly much faster than my original
implementation.
>
> Thank a lot again guys...
>
> Are there any good data structures and algorithms books for VB that you
may
> know of?
>
> Shawn
>
>
> "Bruno Paris" <nospam_ameba@zg.tel.hr> wrote:
> >Hi, Shawn
> >Here is the code:
> >
> >Option Explicit
> >Private Declare Function GetTickCount Lib "kernel32" () As Long
> >
> >Private Sub Form_Click()
> > Dim s As String, tim As Long
> > tim = GetTickCount ' start timer
> >
> > s = OpenWithString
> >
> > Caption = (GetTickCount - tim) / 1000 ' report time
> >End Sub
> >
> >Public Function OpenWithString() As String
> > Dim b() As Byte
> > Dim flen As Long, i As Long
> > Static hextable(255) As String
> > Static initDone As Boolean
> >
> > If Not initDone Then ' do this only once
> > initDone = True
> > For i = 0 To 15
> > hextable(i) = "0" & Hex(i)
> > Next
> > For i = 16 To 255
> > hextable(i) = Hex(i)
> > Next
> > End If
> >
> > ' Read the file into byte array
> > Open "C:\temp\jde_docs_79.zip" For Binary _
> > Access Read Lock Read Write As #1
> > flen = LOF(1)
> > ReDim b(0 To flen - 1) As Byte
> > Get #1, , b()
> > Close #1
> >
> > ' prepare big string
> > OpenWithString = Space(2 + 2 * flen)
> >
> > ' fill the string (non-API method)
> > Mid$(OpenWithString, 1, 2) = "0x"
> > For i = 0 To flen - 1
> > Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
> > Next
> >End Function
> >
> >
> >When compiling, use advanced optimizations (remove bounds
> > check, remove integer overflow checks)
> >
> >Regards,
> >Bruno
> >
> >
> >Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
> >>
> >>Here is a challenging one....
> >....
> >
> >
>

[Eric D. Burdo]

Rod Stephens has a good algorithms book...

http://www.amazon.com/exec/obidos/AS...2-7980153-2040
942

--

Eric D. Burdo, Red-Leif International
VB Programmer and Consultant
<http://www.redleif.com/vb>

*** Please reply to the newsgroup so all can benefit. ***


"Shawn Wilson" <wilso_s@mailcity.com> wrote in message
news:3989eb97$1@news.devx.com...
>
> Bruno, Roberto:
>
> Thankyou very much for your answers. This code is code is sharp.
> It would have taken me a long time to figure this out.
>
> This code is great.....amazingly much faster than my original
implementation.
>
> Thank a lot again guys...
>
> Are there any good data structures and algorithms books for VB that you
may
> know of?
>
> Shawn
>
>
> "Bruno Paris" <nospam_ameba@zg.tel.hr> wrote:
> >Hi, Shawn
> >Here is the code:
> >
> >Option Explicit
> >Private Declare Function GetTickCount Lib "kernel32" () As Long
> >
> >Private Sub Form_Click()
> > Dim s As String, tim As Long
> > tim = GetTickCount ' start timer
> >
> > s = OpenWithString
> >
> > Caption = (GetTickCount - tim) / 1000 ' report time
> >End Sub
> >
> >Public Function OpenWithString() As String
> > Dim b() As Byte
> > Dim flen As Long, i As Long
> > Static hextable(255) As String
> > Static initDone As Boolean
> >
> > If Not initDone Then ' do this only once
> > initDone = True
> > For i = 0 To 15
> > hextable(i) = "0" & Hex(i)
> > Next
> > For i = 16 To 255
> > hextable(i) = Hex(i)
> > Next
> > End If
> >
> > ' Read the file into byte array
> > Open "C:\temp\jde_docs_79.zip" For Binary _
> > Access Read Lock Read Write As #1
> > flen = LOF(1)
> > ReDim b(0 To flen - 1) As Byte
> > Get #1, , b()
> > Close #1
> >
> > ' prepare big string
> > OpenWithString = Space(2 + 2 * flen)
> >
> > ' fill the string (non-API method)
> > Mid$(OpenWithString, 1, 2) = "0x"
> > For i = 0 To flen - 1
> > Mid$(OpenWithString, 3 + 2 * i, 2) = hextable(b(i))
> > Next
> >End Function
> >
> >
> >When compiling, use advanced optimizations (remove bounds
> > check, remove integer overflow checks)
> >
> >Regards,
> >Bruno
> >
> >
> >Shawn Wilson wrote in message <39874c4a$1@news.devx.com>...
> >>
> >>Here is a challenging one....
> >....
> >
> >
>