Hello,
i'm new here. i'm Pierre, and i'm a C / C++ developper. i have a very little knowledge of VB.
i have a C++ DLL with a few exports, as follow:
Those exports are perfectly functional from a test C++ application, and the DLL runs fine.
However, i'm unable to use them with VB.net. i would like to understand how to call them.
i'm able to call the function that don't require parameters (SCStaticInitializer and SCVersion). This works:
However, this doesn't:
A System.AccessViolationException is thrown when calling SCInstanciate...
The structure expected by the DLL is as follow:
Can someone please tell me what i'm doing wrong? Is it the VB structure that is not correctly declared (How to put a char* in a structure in VB?)? Or maybe the way the function is declared (Return type memory size, etc?)? i have tried to play around with some GCHandles instead of the Strings in the structure, with no luck neither... i have also tried to change the return type of the function, with no joy.
As i'm more experienced with low-level languages, i would like to understand how to manage memory myself within VB, so i can get more granularity control over my variables.
Thank you very much for your help!
Pierre.
i'm new here. i'm Pierre, and i'm a C / C++ developper. i have a very little knowledge of VB.
i have a C++ DLL with a few exports, as follow:
Code:
// Version getter.
SCLibOpt void const* SCCConv SCVersion ();
// Static initializer shortcut.
SCLibOpt void SCCConv SCStaticInitializer ();
// Instanciation / Init / Config / Delete.
SCLibOpt void* SCCConv SCInstanciate (void const *devConfig);
SCLibOpt qint32 SCCConv SCInitialize (void *scHndl);
SCLibOpt qint32 SCCConv SCConfigure (void *scHndl, void const *config);
SCLibOpt void SCCConv SCDelete (void *scHndl);
// Api / Infos / Error.
SCLibOpt qint32 SCCConv SCErrorCode (void *scHndl, quint8 reset=true);
// Start.
SCLibOpt qint32 SCCConv SCStartProcessing (void *scHndl);
// Stop.
SCLibOpt void SCCConv SCStopProcessing (void *scHndl);
// Query documents.
SCLibOpt void SCCConv SCDocumentString (void *scHndl, quint32 docId, quint32 offset, quint8 *outKey, quint8 *outVal);However, i'm unable to use them with VB.net. i would like to understand how to call them.
i'm able to call the function that don't require parameters (SCStaticInitializer and SCVersion). This works:
Code:
Private Declare Function SCStaticInitializer Lib "SCLibrary.dll" () As Long
Private Declare Function SCVersion Lib "SCLibrary.dll" () As String
Sub Main()
SCStaticInitializer()
Console.WriteLine("Statically Initialized.")
Dim szVersion = SCVersion()
Console.WriteLine(szVersion)
End SubCode:
Structure SCDeviceConfig
Public enableLogging As Byte
Public deviceId As Byte
Public dataPath As String
Public locale As String
End Structure
Private Declare Function SCInstanciate Lib "SCLibrary.dll" (ByRef devConf As SCDeviceConfig) As UIntPtr
Sub Main()
'' [......]
Dim devConf As New SCDeviceConfig
devConf.enableLogging = 1
devConf.deviceId = 255
devConf.dataPath = "C:/Some/Path"
devConf.locale = "EN"
Dim scHndl = SCInstanciate(devConf)
Console.WriteLine(scHndl)
End SubThe structure expected by the DLL is as follow:
Code:
// DeviceConfig object.
struct SCLibOpt DeviceConfig {
quint8 enableLogging;
quint8 deviceId;
char *dataPath;
char *locale;
};As i'm more experienced with low-level languages, i would like to understand how to manage memory myself within VB, so i can get more granularity control over my variables.
Thank you very much for your help!
Pierre.