Re: template question
Mike King wrote:
I'm getting the following errors. Can someone help me.
error C2327: 'Graph<N>::vertex' : is not a type name, static, or enumerator
error C2065: 'vertex' : undeclared identifier
template <unsigned int N>
struct Graph
{
struct Set {
unsigned char vertex_index[N];
unsigned char IsMarked ( );
};
vector<unsigned char> vertex;
};
template <unsigned int N> unsigned char Graph<N>::Set::IsMarked ( ) {
return IsMarked<N-1>() | vertex[ vertex_index[N] & 0x7F ];
Don't you get the same error here? 'vertex' is just as non-existent in
this function. Of course, you would not if you never instantiate the
template with the argument other than 0.
}
template<> unsigned char Graph<0>::Set::IsMarked ( ) {
return vertex[0]; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
}
'vertex' is not a member of 'Graph<0>::Set'. It's a *non-static* member
of 'Graph<0>', it does not exist outside of a 'Graph<0>' instance, which
'Graph<0>::Set::IsMarked' has not provided. What is it you're trying to
do? It seems that you think that like in Java an instance of the inner
type exists inside an instance of the outer type, and the outer instance
is somehow magically accessible inside the member functions of the inner
type. Well, sorry to disappoint you, but that's not so in C++. The
members of the inner type has no special relation to the instance and
members of the outer type. An instance of 'Graph::Set' does not have to
have and instance of 'Graph' to exist. Once you get your head around
this, you'll see why the compiler complains.
V
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