Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

[Paulraj G]

Hi All, I am calling a c++ dll from c#. it throwing error like "An unhandled exception of type 'System.AccessViolationException' occurred in exe Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

[DllImport(@"D:\Project\Working\Toolkit-2.0\output\Win32\Debug\ipetk.dll",
EntryPoint = "?GetModuleTypeString@ModuleIndex@Infrastructure@IPETK@@QBE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ",
CallingConvention = CallingConvention.Cdecl)]
static extern string GetModuleTypeString(ModuleType ths);

string ModuleIndex = GetModuleTypeString(ModuleType.IPD);
MessageBox.Show(ModuleIndex.ToString());

how can i resolve this issue..? any help will be appriciated. Thanks

G.Paulraj

[BobJanova]

This one must be in the declaration. What is the return type declared at on the C++ side? Are you sure it is defined as C call convention? I suspect you need to marshal the string differently. See [MarshalAs][^].

[Lost User]

Looks like the definition of your C function should be changed to something like:

extern "C" char* GetModuleTypeString(char*);

STL strings do not work well between managed and unmanaged code.

Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

[Bernhard Hiller]

The error message can also originate from a DEP (data execution protection) problem. If you get the error only when you run your compiled executable directly, but not when you debug from Visual Studio, set the DEP flag off: editbin.exe /NXCOMPAT:NO "$(TargetPath)"