DaniWeb Forum Index > Software Development > C

C RSS

templates and maps

•

Join Date: Jun 2004

Posts: 2,108

Reputation: server_crash is on a distinguished road

Solved Threads: 18

server_crash server_crash is offline

Offline

Postaholic

templates and maps

Apr 17th, 2006

I've got the following code:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
template <typename T> int Histogram<T>::get_occurances(const T& obj)
{
         map<T,int>::iterator find_occur = frequency.find(obj);
 
         if ( find_occur == this->frequency.end() )
         {
            return 0;
         }
 
         return ( find_occur->second );
}
template <typename T> int Histogram<T>::get_occurances(const T& obj)
{
         map<T,int>::iterator find_occur = frequency.find(obj);
         
         if ( find_occur == this->frequency.end() )
         {
            return 0;
         }
         
         return ( find_occur->second );
}

The following line always gives me an error saying ';' expected before find_occur.

map<T,int>::iterator find_occur = frequency.find(obj);

If I change the first argument of the map to something other than T, then it works fine, but I need the template type. Is there something I'm doing wrong?

•

Join Date: Apr 2006

Posts: 8

Reputation: eCharisma is an unknown quantity at this point

Solved Threads: 1

eCharisma

Offline

Newbie Poster

Re: templates and maps

Apr 17th, 2006

A type that depends on a template parameter needs to be qualified with the typename keyword.

Help with Code Tags

(Toggle Plain Text)

template <typename T> int Histogram<T>::get_occurances(const T& obj)
{
         typename map<T,int>::iterator find_occur = frequency.find(obj);
         
         if ( find_occur == this->frequency.end() )
         {
            return 0;
         }
         
         return ( find_occur->second );
}

•

Join Date: Jun 2004

Posts: 2,108

Reputation: server_crash is on a distinguished road

Solved Threads: 18

server_crash server_crash is offline

Offline

Postaholic

Re: templates and maps

Apr 17th, 2006

Ahhh, thank you. I was actually looking into using a typename, but in a different context. I've never really understood why you have to qualify it with that.

Thanks man.