map using a template value
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  1. #1
    Join Date
    Aug 2009
    Posts
    2

    map using a template value

    I've written the following code, i want to use my own hash map and overwrite the find function suitably. my map values are of type packet_entry_t.

    #ifndef SIM_A_CX_SW_PACKET_STORAGE_H
    #define SIM_A_CX_SW_PACKET_STORAGE_H


    #include <map>

    #ifdef LOG_PACKET_TIMES
    #include <iostream>
    #include <fstream>
    #include <cstring>
    #endif // LOG_PACKET_TIMES

    template <class TTileAddress_t>
    class packet_storage {

    private:
    typedef packet_entry_t<TTileAddress_t> pkt_entry_t;


    typedef std::map<unsigned int, pkt_entry_t>::iterator iterator_t;

    map<unsigned int, pkt_entry_t> pkts_map;

    public:
    packet_storage();
    ~packet_storage();

    // problem 1
    typename std::map<unsigned int, pkt_entry_t>::iterator it;

    //problem 2
    std::map<unsigned int, pkt_entry_t>::iterator find(unsigned int a , unsigned int b);
    std::map<unsigned int, pkt_entry_t>::iterator find(unsigned int );

    }; // end class packet_storage
    #endif //end packet_storage_h


    i receive errors in line //problem 1 and //problem 2 as follow.

    //problem 1 erro:::
    type ‘std::map<unsigned int, packet_entry_t<TTileAddress_t>, std::less<unsigned int>, std::allocator<std:air<const unsigned int, packet_entry_t<TTileAddress_t> > > >’ is not derived from type ‘packet_storage<TTileAddress_t>’

    //problem 2 error:::
    error: type ‘std::map<unsigned int, packet_entry_t<TTileAddress_t>, std::less<unsigned int>, std::allocator<std:air<const unsigned int, packet_entry_t<TTileAddress_t> > > >’ is not derived from type ‘packet_storage<TTileAddress_t>’


    CAN ANY BODY TELL ME WHY? AND HOW CAN I SOLVE THE PROBLEM
    I SOULD BE GRATEFUL.
    THANKS
    ATEFE

  2. #2
    Join Date
    Jul 2002
    Location
    Portsmouth. United Kingdom
    Posts
    2,699

    Re: map using a template value

    This compiles, after supplying my own packet_entry_t structure.

    Code:
    template<class TTileAddress_t>
    class packet_storage
    {
    private:
        typedef packet_entry_t<TTileAddress_t>                pkt_entry_t;
    
        typedef typename std::map<unsigned int, pkt_entry_t>::iterator iterator_t;
    
        std::map<unsigned int, pkt_entry_t> pkts_map;
    
    public:
        packet_storage();
        ~packet_storage();
    
    // problem 1
        typename std::map<unsigned int, pkt_entry_t>::iterator it;
    
    //problem 2
        typename std::map<unsigned int, pkt_entry_t>::iterator find(unsigned int a,
                                                                    unsigned int b);
        typename std::map<unsigned int, pkt_entry_t>::iterator find(unsigned int);
    }; // end class packet_storage
    It mostly needed more 'typename' keywords.

    BTW I see no hash map!
    "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong."
    Richard P. Feynman

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