How to declare an iterator to
std::map <T, Point <T> *> ,
where:
template <typename T>
struct TList
{
typedef std::vector < std::map <T, Point <T> *> > Type;
};
In the following code
int main ()
{
....
std::map <T, Point <T> *> ::iterator i_map; //Error
...
}
g++ shows this error:
error: dependent-name ` std::map<T,Point<T>*,std::less<_Key>,std::allocator<std::pair<const T, Point<T>*> > >::iterator' is parsed as a non-type, but instantiation yields a type
note: say `typename std::map<T,Point<T>*,std::less<_Key>,std::allocator<std::pair<const T, Point<T>*> > >::iterator' if a type is meant
Use typename
as:
typename std::map<T, Point <T> *>::iterator i_map;
//^^^^^^^^ here!
Because iterator
is a dependent-name (as it depends on the map's type argument T
), so typename
is required here.
Read this FAQ for detail explanation:
Where and why do I have to put the "template" and "typename" keywords?
Put " typename
" before the line of error : std::map <T, Point <T> *> ::iterator i_map;
.
Example:
typename vector<T>::iterator vIdx;
// On your case : typename std::map <T, Point<T>*>::iterator i_map;
vIdx= find(oVector->begin(), oVector->end(), pElementToFind); //To my case
Does typename std::map <T, Point <T> *> ::iterator i_map;
work?
那么typename TList<T>::Type::value_type::iterator
呢?
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