I have implemented IPC mechanism using RegisterWindowMessage .
The sending app allocates memory using GlobalAlloc and gets the pointer using GlobalLock and casts it to ptr to struct and assigns value to it. Then it calls GlobalUnlock and sends the HGLOBAL as lparam of PostMessage. The receiving app converts the HGLOBAL into
a pointer(GlobalLock) and the pointer is not NULL. But when I try to read the contents of the pointer I get an access violation. I tried various ways of GlobalLock etc but in vain.