VB 6 API Programming

[g_bhujbal]

I would like to design the program in VB 6.0 for the following activity:
1) open the Excel file
2) Read the API function name, required parameters value.
3) Call the API
4) Store the result in other excel file.

Is it possible with VB 6.0?

Please help.

[moa]

hello,

1) open the Excel file
2) Read the API function name, required parameters value.
3) Call the API
4) Store the result in other excel file.

I hardly understand (just guess... without being quite sure)

1) what does "open the Excel file" mean ? would it be "open an existing and known excel File ?

2) When tou say " Read the API function name, required parameters value",; what do you exactly mean ? Read from where ?

[PeejAvery]

If you are talking about the API calls being held in an Excel file, then no, you cannot. You cannot add and subtract code from an EXE during runtime.

If you desire to write a log file, that is very simply done, but why you would use Excel for that, I don't know. Do some searching in the forums. Plenty of code is provided to help you work with Excel.

[bushmobile]

You cannot add and subtract code from an EXE during runtime.

True, but you can dynamically load and call procedures within DLLs.

Use LoadLibrary to load the dll, GetProcAddress to get the address of the function, and, at it's most simple use CallWindowProc to call the function: Example at AllAPI.net

You're limited to 4 parameters using CallWindowProc and I'm not sure passing 0& to unused parameters is completely safe, but you can circumvent this by using SoftCircuits' CallPtr dll:

Private Declare Function FreeLibrary Lib "kernel32" ( _
    ByVal hLibModule As Long) As Long
    
Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" ( _
    ByVal lpLibFileName As String) As Long
    
Private Declare Function GetProcAddress Lib "kernel32" ( _
    ByVal hModule As Long, ByVal lpProcName As String) As Long
    
Private Declare Function CallAPI Lib "CALLPTR.DLL" Alias "scCallPtr" ( _
    ByVal pProc As Long) As Long
    
Private Declare Function CallAPIWithArgs2 Lib "CALLPTR.DLL" Alias "scCallPtr" ( _
    ByVal pProc As Long, ByVal arg1 As Any, ByVal arg2 As Any) As Long

Private Sub Command1_Click()
    Dim hLib As Long, hProc As Long
    
    hLib = LoadLibrary("user32")
    
    hProc = GetProcAddress(hLib, "SetWindowTextA")
    Debug.Print CallAPIWithArgs2(hProc, Me.hWnd, "Test")
    
    hProc = GetProcAddress(hLib, "GetDesktopWindow")
    Debug.Print CallAPI(hProc)
    
    FreeLibrary hLib
End Sub

[PeejAvery]

True, but you can dynamically load and call procedures within DLLs.

Ah yes. How could I forget that.

[ChaosTheEternal]

There is also a pure VB way of doing that:
http://www.planet-source-code.com/vb...32873&lngWId=1

Nifty piece of code lets you put DLLs wherever and call their functions, not just force them into the system32 directory or add to the PATH environment variable.

I've only tested it with a DLL that takes two strings as it's parameters, but that works perfectly.

[g_bhujbal]

Thanks Bushmobile.
you got it right what I actually want to say.
Still SoftCircuits' CallPtr.dll having limitation i.e. you cannot use a string
argument here because Visual Basic converts strings to ANSI when calling DLL functions.
Some functions which I need to call requires string parametr then how to tackle this problem.

PeejAvery:
"you can dynamically load and call procedures within DLLs."
Plesae tell me how to do this. Code sample will be very helpful.

[bushmobile]

Thanks Bushmobile.
you got it right what I actually want to say.
Still SoftCircuits' CallPtr.dll having limitation i.e. you cannot use a string
argument here because Visual Basic converts strings to ANSI when calling DLL functions.

I used a string in my example.

PeejAvery:
"you can dynamically load and call procedures within DLLs."
Plesae tell me how to do this. Code sample will be very helpful.

he was quoting me, and i demonstrated it in my post, also check out ChaosTheEternal's post


@ChaosTheEternal: nice link!

[g_bhujbal]

Thanks