Error C3918: Error wile checking event for being nullptr

问题

I have delegate and event in my .h file

delegate void ResponseReceivedHandler(System::Object^ sender, WhoisEventArgs^ e);
event ResponseReceivedHandler^ ResponseReceived; 

somewhere in my code I want to check if event is nullptr or no, but when I write

EDITED:

if (this->ResponseReceived != nullptr)
{
     this->ResponseReceived(this, e);
}

Error occurred

Error 1 error C3918: usage requires 'VT::WhoisClient::WhoisRequest::ResponseReceived' to be a data member c:\Users\ViToBrothers\Desktop\ViTo Projects\VT.WhoisClient\VT.WhoisClient\VT.WhoisRequest.cpp 50

What can I do ?

回答1:

I believe that in this case, the compiler is generating the accessor functions and backing storage for the event handler delegate. Thus, it is not necessary for you to check for null.

See more here: http://msdn.microsoft.com/en-us/library/4b612y2s.aspx

来源：https://stackoverflow.com/questions/6034720/error-c3918-error-wile-checking-event-for-being-nullptr