User-Defined Conversions
This section discusses user-defined conversions (UDC) when one of the types in the conversion is a reference or instance of a value type or reference type.
Remarks
A user-defined conversion can either be implicit or explicit. A UDC should be implicit if the conversion does not result in a loss of information. Otherwise an explicit UDC should be defined.
A native class's constructor can be used to convert a reference or value type to a native class.
For more information about conversions, see Implicit Boxing and Standard Conversions.
This section contains the following topics:
Example
// mcpp_User_Defined_Conversions.cpp
// compile with: /clr
#include "stdio.h"
ref class R;
class N;
value class V {
static operator V(R^) {
return V();
}
};
ref class R {
public:
static operator N(R^);
static operator V(R^) {
System::Console::WriteLine("in R::operator N");
return V();
}
};
class N {
public:
N(R^) {
printf("in N::N\n");
}
};
R::operator N(R^) {
System::Console::WriteLine("in R::operator N");
return N(nullptr);
}
int main() {
// Direct initialization:
R ^r2;
N n2(r2); // direct initialization, calls constructor
static_cast<N>(r2); // also direct initialization
R ^r3;
// ambiguous V::operator V(R^) and R::operator V(R^)
// static_cast<V>(r3);
}
in N::N
in N::N