Program crashes when calling function from DLL when trying to copy an array

Question

Today I tried to make my first DLL and my first application which would use a DLL.

The DLL is made in C++ and this is the code I'm calling:

void Graph::findPath_r(Node* pStart, Node* pEnd, std::vector<cell> &road, cell &costMx)
{
//.....
    if(pEnd->getParent() != NULL)
    {
        while(!path.empty())
        {
            road.push_back(path.top()->getName());
            costMx += path.top()->getGCost();
            path.pop();
        }
        return;
    }
    return;
}
vector <int>tbcway;
int FUNCTION CalculatePath(int Start, int End, int * Array, int &cost)
{
    dgraph->findPath_r(xNode[Start].NodeID ,xNode[End].NodeID,tbcway,cost); 
    dgraph->reset();
    std::copy(tbcway.begin(), tbcway.end(), Array);
    tbcway.clear();
    return 1;
}

and this is how I declared it in VB.net and called it:

Imports System.Runtime.InteropServices

Public Class Form1

<DllImport("RCP.dll")> _
Public Shared Function LOAD_SYSTEM() As Boolean
End Function

<DllImport("RCP.dll")> _
Public Shared Function GetPluginVersion() As Integer
End Function

<DllImport("RCP.dll")> _
Public Shared Function CalculatePath(ByVal StartNode As Integer, ByVal EndNode As Integer, ByRef Array() As Array, ByRef cost As Integer) As Integer
End Function

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    LOAD_SYSTEM()
    MsgBox(GetPluginVersion().ToString())
    Dim path(4096) As Array
    Dim movecost As Integer
    CalculatePath(1702, 27932, path, movecost)
End Sub
End Class

So, what is wrong with this code? The error I am getting is:

A call to PInvoke function 'RCP GUI!RCP_GUI.Form1::CalculatePath' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

i don't know vb.net but that "as array" looks pretty suspicious. unless vb has some built-in thing that's called "array" and that's an array of integers? — Cheers and hth. - Alf, Nov 28 '12 at 21:38
the path calculation works flawless as it works in another application which also uses C++ — , Nov 28 '12 at 21:38
isn't there any way to say that hey, this is an array *of integers*? — Cheers and hth. - Alf, Nov 28 '12 at 21:41
maybe checking what your DLL exports would help, e.g. `dumpbin /exports RCP.dll` ? — Nate Kohl, Nov 28 '12 at 21:45
the explorts are there because GetPluginVersion returns the correct version number. — , Nov 28 '12 at 21:46
i googled and clicked first hit and i think you can declare it like `<[In](),Out()> ByVal x As Integer()`. — Cheers and hth. - Alf, Nov 28 '12 at 21:53
also see http://blogs.msdn.com/b/vbteam/archive/2008/06/20/pinvoke-interop-assistant-on-codeplex.aspx (tool to generate signatures for pinvoke, if i understand it right) — Cheers and hth. - Alf, Nov 28 '12 at 21:55
still the unbalanced stack message : ( however visual studio didn't crash now :P — , Nov 28 '12 at 21:56
Are you compiling on 64bit or 32 bit. On 64 bit, I do not think Integer is the same size as a pointer. — John Bandela, Nov 28 '12 at 21:56
the <[In](),Out()> ByVal x As Integer(). stuff works, i just get a warning that the stack is unbalanced, but the application works. — , Nov 28 '12 at 22:01
it works great now, this helped me: http://stackoverflow.com/questions/2390407/pinvokestackimbalance-c-sharp-call-to-unmanaged-c-function — , Nov 28 '12 at 22:03
@Cheersandhth.-Alf you deserve to answer and let the answer be accepted :) — , Nov 28 '12 at 22:04

score 0 · Accepted Answer · answered Nov 28 '12 at 23:18

0

This is probably a calling convention mismatch.

Try decorating your DllImport with different calling conventions to see which works (my guess is that it should be cdecl).

answered Nov 28 '12 at 23:18

Rolf Bjarne Kvinge

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Program crashes when calling function from DLL when trying to copy an array

1 Answers1