_CrtIsValidHeapPointer (Puserdata)

The program encountered title run times error, refer to the following text, take the custom class's object definition to new mode generation after the problem resolution.

！！ Expression: _CrtIsValidHeapPointer (Puserdata)

void Cimagerecview::onfilecolhistogram ()
{
Todo:add your command handler code here
Cimagerecdoc *pdoc = GetDocument ();
LPSTR Lpdib;

Colhistogram mycolhist;

Lpdib = (LPSTR):: GlobalLock ((HGLOBAL) Pdoc->gethdib ());

PMYCOLHIST->RGBTOHSV (LPDIB);

:: GlobalUnlock ((HGLOBAL) Pdoc->gethdib ());
}

The problem is in the red place, customizing a class

Change the above statement to

Colhistogram * pmycolhist;
Pmycolhist = new Colhistogram;

Yes, but now I don't know why.

This paragraph in the (MSDN)

The   _crtisvalidheappointer   function   is   used   to   ensure   this   a &nbsp ; Specific   memory   address   is   within   the   local   heap.   The   "local"   heap   refers   to   the   heap   created   and   mana Ged   by   a   particular   instance   of   the   C   run-time   Library.   If   A   dynamically   linked   library   (DLL)   contains   a   static &NB Sp Link   to   the   run-time   Library,   then   it   have   its   own   in Stance   of   the   run-time   heap,   and   therefore   its   own   heap, &N Bsp Independent   of   the   application ' s   local   heap.   When   _DEBUG   are   not   defined,   calls   To   _CrtIsValidHeapPointer   is   removed   during   preprocessing.

See this paragraph slightly feel a little bit of meaning, I in the program myself applied for the local heap, also have to generate dynamic connection Library of the Dib class, to connect the C runtime Library, then my Colhistogram instance must be dynamically generated, because it does not have a corresponding heap in the C run-time library. For example, I add CString str, the program will not have a problem, but I only know that CString is a system-defined, and the C run-Library has nothing to do with it. If you statically link the C runtime, then the DLL will have a local heap independent of the application (the EXE that called it) (but my program does not), and if _DEBUG is not defined, the _CrtIsValidHeapPointer is removed by the preprocessor. That's probably the way it is, I'm not sure of a lot of what I'm saying, it's just an explanation.

Possible causes: DLLs and EXE main programs are not created using the same heap.

Workaround:

1. The principle of who assigns who to release;

2. Bypass new and delete, using Glovalalloc and GlobalFree;

3. Change the project options, release version certainly will not have this failure, this will only exist in the debug state, but release will have a memory leak. Change debug under DLL and EXE runtime for dynamic compilation i.e.: Multi-threaded Debug DLL. Because the Multi-thread debug DLL is compiled by the runtime, the compiler allocates the heap for all DLLs that are shared. This will not have multiple release procedures, and there will be no problem.

_CrtIsValidHeapPointer (Puserdata)