Question

I am having problems with the syntax in c++/cli when I try to define a c++/cli value struct as a TValue in a Dictionary

I am doing this because I want to maintain a map between a native class pointer and a system::String (with String as the key), so have wrapped the native pointer in a struct.

value struct MyStruct
{
   NativeClass *m_p;
}

Dictionary<System::String ^, MyStruct> MyMap;

NativeClass* FindLigandModelMap(System::String ^file)
{
   MyStruct m;
   if (m_LigandToModelMap.TryGetValue(file, %m)) <--- ERROR HERE
      return(m.m_p);
   return(NULL);
}

Thi gives a compiler error: error C2664: ‘System::Collections::Generic::Dictionary::TryGetValue’ : cannot convert parameter 2 from ‘MyStruct ^’ to ‘MyStruct %’

I have tried various declarations of MyStruct with no success.

Answer 1

Should be just

m_LigandToModelMap.TryGetValue(file, m)

In C++, byref arguments don’t provide any caller-side hint.