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Re: Iterator in a template

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On 1/18/2012 8:49 PM, Pierre Abbat wrote:
> I've used map iterators before; this is my first time making a template.
> hvec (hexagonal vector) is an integral (in the mathematical sense) type
> representing a point in a hexagonal lattice. A harray is an array
> subscripted by an hvec. Currently I use only bytes as the elements, but I
> will need to store larger things in harrays, so I made it a template. I
> wrote this code to clear all elements in the harray:
>
> template<typename T>  class harray
> {map<hvec,T *>  index;
>   public:
>   T&  operator[](hvec i);
>   void clear();
>   };
>
> template<typename T>  T&  harray<T>::operator[](hvec i)
> {hvec q,r;
>   q=i/PAGEMOD;
>   r=i%PAGEMOD;
>   if (!index[q])
>      index[q]=(T*)calloc(PAGESIZE,sizeof(T));
>   return index[q][r.pageinx()];
>   }
>
> template<typename T>  void harray<T>::clear()
> {map<hvec,T *>::iterator i; // line 78
>   for (i=index.start();i!=index.end();i++)
>       {free(i->second);
>        i->second=NULL;
>        }
>   }
>
> When I try to compile it, I get this error:
>
> In file included from /home/phma/hexcode/hexcode.cpp:5:
> /home/phma/hexcode/hvec.h: In member function 'void harray<T>::clear()':
> /home/phma/hexcode/hvec.h:78: error: expected ';' before 'i'
> /home/phma/hexcode/hvec.h:79: error: 'i' was not declared in this scope
>
> How can I fix it?

hmap<>::iterator is a dependent type.  use
"typename map<hvec, T*>::iterator"

I believe this is in the FAQ

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Thread

Iterator in a template Pierre Abbat <phma@phma.optus.nu> - 2012-01-19 04:49 +0000
  Re: Iterator in a template red floyd <no.spam.here@its.invalid> - 2012-01-18 22:36 -0800
    Re: Iterator in a template Pierre Abbat <phma@phma.optus.nu> - 2012-01-19 13:05 +0000
  Re: Iterator in a template "MikeWhy" <boat042-nospam@yahoo.com> - 2012-01-19 05:44 -0600
    Re: Iterator in a template SG <s.gesemann@gmail.com> - 2012-01-19 06:08 -0800

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