请问:vb.net调用vc写的dll出错:报尝试读取或写入受保护的内存

请教:vb.net调用vc写的dll出错:报尝试读取或写入受保护的内存
vb,net调用dll中的unsigned char getbitchar(IN struct st cl,OUT unsigned char b[]),报尝试读取或写入受保护的内存。这通常指示其他内存已损坏。
这个函数在vb.net下应该怎么写?

[解决办法]
1.首先你要定义好结构体

VB.NET code

    <StructLayout(LayoutKind.Sequential, Pack:=1)> _    Public Structure st        'INT型        Dim countAs Int32        'Char[]数组类型        <MarshalAs(UnmanagedType.ByValArray, ArraySubType:=UnmanagedType.ByValTStr, Sizeconst:=80)> _        Dim string() As Byte    End Structure
[解决办法]
Public Structure cardlayout  
       Dim a As Int16 ===>int32
       Dim b As Int16 ===>int32
       Dim c As Int16 ===>int32
       Dim d As Int16 ===>int32
       Dim e As Int16 ===>int32
       Dim f As Int16 ===>int32
       Dim g As Int16 ===>int32
       Dim h As Int16 ===>int32
       Dim i As Int16 ===>int32
       Dim j As Int16 ===>int32
       Dim k As Int16 ===>int32
       Dim l As Int16 ===>int32
       Dim m As Int16 ===>int32
       Dim n As Integer  
   End Structure  


<DllImport("your.dll", CharSet:=CharSet.Ansi) > Public Shared Function SetStaticStruct(Byval str() As Byte, ByRef cl As cardlayout) 

   End Function  
    <DllImport("your.dll", CharSet:=CharSet.Ansi) > Public Shared Function getbitchar(ByRef cl As cardlayout, ByValstr() As Byte) 
   End Function