Either I'm doing MID$( wrong or it has a bug

[TDarcos]

Here is a program to extract a web page and find a string. But sometimes it doesn't work. Check it out:

Code: (Select All)

$Unstable:Http

$Console:Only

Dim Url As String

ReDim Shared As String Res(0), All

Dim h As Long, s As String, F As Long

Const Site = "//commons.wikimedia.org"

Url = "/w/index.php?title=SpecialrefixIndex&from=BSicon_gPSLr.svg&prefix=BSicon&namespace=6"



Dim R As String

Dim As Long Target, Count, Location

10 '

GoSub DownLoad 'Site + Url, sc&, Count&

If SC <> 0 Then 99



Print "Number of lines"; Count

Print "found at pos"; Location; "on line"; Target

Print "All size"; Len(All); " found at";

F = InStr(All, "Next page (BSicon")

Print F

K$ = Mid$(All, F, 10)

Print "K size"; Len(K$)

Print "K$='"; K$; "'"













Print "Extract follows -200 to +200"

Extract$ = Mid$(All, F - 200.40)

Print "Len="; Len(Extract$)

Print

Print Extract$









End





99 '

Print

Print "Status code"; SC; " on: "; Url

Print

Print "Do you want to continue";

Input Ans$

If UCase$(Left$(Ans$, 1)) = "Y" Then GoTo 10

If UCase$(Left$(Ans$, 1)) <> "N" Then GoTo 99

Print

End





DownLoad:



Count = 0

ReDim Res(Count)

All = ""

h = _OpenClient("HTTP:" + Site + Url)



statusCode = _StatusCode(h)



While Not EOF(h)

    _Limit 60

    Get #h, , s

    All = All + s

    Count = Count + 1

    ReDim _Preserve Res(Count)

    F = InStr(s, "Next page (BSicon")

    If F <> 0 Then

        Target = Count

        Location = F

    End If

    Res(Count) = s





Wend



Close #h

Return







'  Content of the HTTP response is returned.

' The statusCode is also assigned.

Function DL$ (url As String, statusCode As Long)

    Dim h As Long, content As String, s As String



    h = _OpenClient("HTTP:" + url)



    statusCode = _StatusCode(h)



    While Not EOF(h)

        _Limit 60

        Get #h, , s

        content = content + s

    Wend



    Close #h



    DL$ = content

End Function

Sub xDownLoad (url As String, statusCode As Long, Count As Long)

    Dim h As Long, content As String, s As String





    h = _OpenClient("HTTP:" + url)



    statusCode = _StatusCode(h)



    While Not EOF(h)

        _Limit 60

        Get #h, , s

        content = content + s

    Wend



    Close #h





End Sub

I tried different things to figure out what I did wrong, because this was the result:

Number of lines 7
found at pos 9182 on line 7
All size 82640  found at 36715
K size 10
K$='Next page '
Extract follows -200 to +200
Len= 46126

/div></fieldset></form></div><div class="mw-prefixindex-nav"><a href="/w/index.php?title=SpecialrefixIndex&amp;from=BSicon_geBHF-L.svg&amp;prefix=BSicon&amp;namespace=6" title="SpecialrefixIndex">Next page (BSicon geBHF-L.svg)</a></div><div class="mw-prefixindex-body"><ul class="mw-prefixindex-list"><li><a href="/wiki/File:BSicon_gPSLr.svg" title="File:BSicon gPSLr.svg">BSicon gPSLr.svg</a></li>
<li><a href="/wiki/File:BSicon_gS%2BBHF.svg" title="File:BSicon gS+BHF.svg">BSicon gS+BHF.svg</a></li>
<li><a href="/wiki/File:BSicon_gSBHF.svg" title="File:BSicon gSBHF.svg">BSicon gSBHF.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI1%2Br.svg" title="File:BSicon gSHI1+r.svg">BSicon gSHI1+r.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI1l.svg" title="File:BSicon gSHI1l.svg">BSicon gSHI1l.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2%2Bl.svg" title="File:BSicon gSHI2+l.svg">BSicon gSHI2+l.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2%2Br.svg" title="File:BSicon gSHI2+r.svg">BSicon gSHI2+r.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2c1.svg" title="File:BSicon gSHI2c1.svg">BSicon gSHI2c1.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2c2.svg" title="File:BSicon gSHI2c2.svg">BSicon gSHI2c2.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2c3.svg" title="File:BSicon gSHI2c3.svg">BSicon gSHI2c3.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2c4.svg" title="File:BSicon gSHI2c4.svg">BSicon gSHI2c4.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2l.svg" title="File:BSicon gSHI2l.svg">BSicon gSHI2l.svg</a></li>
<li><a href="/wiki/File:BSicon_gSHI2r.svg" title="File:BSicon gSHI2r.svg">BSicon gSHI2r.svg</a></li>

I'll spare you the next 30,000 chars, but you get the idea. It does correctly copy the preceding 200 bytes, but fails to stop at 400. I note, when I check the first line of output in Notepad++ the search string beginning "Next Page" is correctly at byte 201:

/div></fieldset></form></div><div class="mw-prefixindex-nav"><a href="/w/index.php?title=SpecialrefixIndex&amp;from=BSicon_geBHF-L.svg&amp;prefix=BSicon&amp;namespace=6" title="SpecialrefixIndex">Next page (BSicon

So any assistance you can offer me is appreciated.

- - - -
Paul

[DSMan195276]

> Extract$ = Mid$(All, F - 200.40)

Is that supposed to be `Mid$(All, F - 200, 400)`?

[SMcNeill]

Aye, there's no length set in that MID$ statement.   I think Matt has the issue pegged squarely. 

[TDarcos]

Never mind, I now see exactly where I made a mistake. Instead of , separating the arrguments to MID$, I had a . which told it to take F-200.40, so it copied from F-200 to the end of the string. But I only noticed it when I was reading the message I had posted here.

So maybe it was worth it.

[TDarcos]

Thank you, everyone! I never expected am answer this quickly. I figured I did something wrong, but I couldn't see it. However, on rare occasions I have discovered actual bugs in a compiler. Usually it is my error, and that's what I figured, but I just couldn't see it (at the time.)