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How to pass CString as argument to the PostMessage? and again how to convert LPARAM/WPARAM back to CString? Help me!

1 solution

You don't.
When you post a message, you don't know when it will be received. It can be received after the string you want to pass is already out of scope.
If you're posting a message to another window in the same process, use the source/sink idiom (AKA producer/consumer):

void producer()
    wchar_t * wstring = new wchar_t[80];
    wcscpy(wstring, L"HELLO");
    ::PostMessage(HWND, MY_CUSTOM_MESSAGE, 0, (LPARAM) wstring);
    // DO NOT DELETE wstring;

class Consumer
    LRESULT On_MyCustomMessage(WPARAM /*notused*/, LPARAM lpWstring)
        wchar_t *pString = (wchar_t *) lpWstring;
        // Do something with pString... You can even pass it to a CStringW constructor. 
        delete[] pString; // and don't forget this!
        return 0L;

If you're using CString, see the AllocSysString() member function. BSTRs are meant to be passed around.

Hope this helps,
Member 12038742 7-Oct-15 3:29am
where do I place the consumer in my code?
Pablo Aliskevicius 8-Oct-15 2:20am
Typically, in the class that receives the message that was posted. It may handle the message by converting the raw pointer to a CString or CStringW, passing it to the business logic API that required it in the first place, and deleting it.

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