templates and maps

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I've got the following code:

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?

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server_crash

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Postaholic

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since Jun 2004

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Apr 17th, 2006

Re: templates and maps

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

(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 );
}

eCharisma

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Newbie Poster

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since Apr 2006

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Apr 17th, 2006

Re: templates and maps

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.

server_crash

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Postaholic

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