Question

I need to make last argument in my function to be a default argument and the type of this argument is *& (reference to pointer). For some reason this doesn’t work for me:

template<class T>
void f(T*& = nullptr);  

I’m getting an error:

Error 1 error C2440: ‘default argument’ : cannot convert from ‘nullptr‘ to ‘T *&‘

How to get around this?

Answer 1

Basically, if you need to call this function with nullptr (which means “I don’t have a value to pass to the function, but want to call it anyway”), then you would want to take the argument per T**.

See How to pass objects to functions in C++? for more on passing arguments.