LoadLib again

[Scott Turchin]

Interesting, but For some reason whether this function does not exist (It does, saw msdn on it) or what, I'm confused.

Why do I have to declare the function, and then NOT be able to run the app because the function is not found in KERNEL32.DLL.

If the function is not found I want to drive on, continue etc....
But I can't run the function without declaring it??


Thanks,

Scott

'Declare Function IsDebuggerPresent Lib "kernel32" () As Long

hLib = LoadLibrary("KERNEL32.DLL")
procaddr = GetProcAddress(hLib,"IsDebuggerPresent")
If IsFalse procaddr Then
   MsgBox "Could not find the function, or DLL:" & $CRLF & "IsDebuggerPresent, in KERNEL32.DLL",%MB_ICONSTOP,"Error loading library"
Else
   Call Dword ProcAddr Using IsDebuggerPresent()
End If

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Scott
mailto:[email protected][email protected]</A>

[Scott Turchin]

Wait a second....

If I rem out the actual Call Dword using then it runs, so it loads the lib just fine.


So if the function does not exist, I should not try to run it but it still stops the app just by being compiled, it never even executes...
So how can you tell if a DLL has the right function, if you attempt to load and can't you should be able to continue..

I forgot how to do this..hehe..


Scott

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Scott
mailto:[email protected][email protected]</A>

[Edwin Knoppert]

You need to Alias the call.
Or if you need late loading, use a prototype without the DLL name


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[Chris Boss]

Scott;

When using the CALL DWORD command you must always "prototype" the
function/procedure call in a declare statement !

ie.

Declare Function IsDebuggerPresentX () As Long

...

hLib = LoadLibrary("KERNEL32.DLL")
procaddr = GetProcAddress(hLib,"IsDebuggerPresent")
If IsFalse procaddr Then
   MsgBox "Could not find the function, or DLL:" & $CRLF & "IsDebuggerPresent, in KERNEL32.DLL",%MB_ICONSTOP,"Error loading library"
Else
   Call Dword ProcAddr Using IsDebuggerPresentX()
End If

You will notice the Declare statement doesn't need the LIB option, since
you are using LoadLibrary !

Also, you will notice I added a capital X to the procedure name. This is not required
or necessary, but I do suggest always added a prefix or suffix to
the actual procedure/function name to indicate to you that the declaration
is to be used as a prototype for CALL DWORD. I like to simply add
a capital X as a suffix, since it is simple.


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[Scott Turchin]

Now that kinda makes some sense, except that the X has no value to it...or is that the point?

I'll give it a shot, the docs say thefunction exists, my Win2k box says it does not
Maybe it's for when you are in debug mode..


Thanks!

Scott

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Scott
mailto:[email protected][email protected]</A>

[Semen Matusovski]

This function works fine on my PC under Win2000.
Run a fragment in normal mode and under PB/DLL debugger.

   #Compile Exe
   #Dim All
   #Register None
   #Include "Win32Api.Inc"

   Declare Function IsDebuggerPresent As Long
   
   Function PbMain
      Dim hLib As Long, hProc As Dword, lResult As Long
      hLib = LoadLibrary("KERNEL32.DLL")
      hProc = GetProcAddress(hLib,"IsDebuggerPresent")
      If IsFalse(hProc) Then lResult = 0 Else _
         Call Dword hProc Using IsDebuggerPresent To lResult
      If lResult Then MsgBox "Under debugger" Else MsgBox "Don't see a debugger"
   End Function

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E-MAIL: [email protected]

[Chris Boss]

Scott;

The thing with the X in the Prototype Declaration is just something
I do to distiguish Prototype Declarations from normal ones.

When you go back to your code months later, you may think you are
defining procedures in your own code (since if the LIB part is not
there, it is likely a local declaration), rather than just a
prototype declaration.

It helps me read my own code later on, when I go back to it.


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[Lance Edmonds]

The thing with the X in the Prototype Declaration is just something
I do to distiguish Prototype Declarations from normal ones.

Or to put it another way: to distinguish between implicitly imported functions and explicitly imported functions. It is an good idea!



------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>