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c ++ map

hey i wanna sort ma map using the second value which is an int.help me do this

Map:
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  1.    class MyMap
  2.    {
  3.    public:
  4.        typedef string                   KeyType;
  5.        typedef int                           ValueType;
  6.        typedef pair<KeyType, ValueType> ItemType;
  7.  
  8.    private:
  9.        typedef map<KeyType, ValueType>  MapType;
  10.        MapType   map_;
  11.  
  12.    public:
  13.  
  14.        bool  AddItem( KeyType const & k, ValueType const & v )
  15.        {
  16.        // insert returns a std::pair of the position
  17.        // and whether the insertion succeeded.
  18.        // We are only interested in the success value.
  19.          return map_.insert( make_pair(k,v) ).second;
  20.        }
  21. bool comp_int(const int &s1, const int  &s2)
  22. {
  23.   return(s1>s2 ? true:false);
  24. }
  25.        bool Find( KeyType const & k, ValueType & v )
  26.        {
  27.          //sort(map_.begin(),map_.end());//needs to be sorted before the search happens.sorted in ascending order.the int value(i.e the v should be used for sorting)
  28.          MapType::iterator pos( map_.find(k) );
  29.          if ( pos != map_.end() )
  30.          {
  31.              v = pos->second;
  32.              return true;
  33.          }
  34.          else
  35.          {
  36.              return false;
  37.          }
  38.        }
  39.    };
  40.  
Main:
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  1.    int main()
  2.    {
  3.        MyMap p1;
  4.  
  5.        for(int i=0;i<5;i++)
  6.        {
  7.             cout << "enter mac_addr value pair: ";
  8.             MyMap::KeyType key;
  9.             MyMap::ValueType value;
  10.             cin >> key;
  11.             cin >> value;
  12.              p1.AddItem(key, value) ;
  13.             //{
  14.               //   cerr << "Mac address duplicate, data not stored." << endl;
  15.             //}
  16.        }
  17.  
  18.        cout << "Enter mac address to lookup: ";
  19.        MyMap::KeyType searchKey;
  20.        cin >> searchKey;
  21.        MyMap::ValueType foundValue;
  22.        if ( p1.Find( searchKey, foundValue) )
  23.        {
  24.            cout << "Found value " << foundValue << " for search key " << searchKey << endl;
  25.        }
  26.        else
  27.        {
  28.            p1.AddItem(searchKey,0);
  29.            cout << "No such mac address as " << searchKey << " in map." << endl;
  30.        }
  31.        return 0;
  32.    }
  33.  
//in this u have to sort the map inoder to compare properly.coz in this what happpens is when u insert the lastest ack,it is stored behind coz first in first out concept.so when it searches it encounters the first inserted sender and ack which mite be incorrect.
//so c if u can sort the map
Oct 14 '08 #1
4 1525
gpraghuram
1,275 Expert 1GB
Whe you define a map you can use the 3rd paramater to define your own comparison function.
Try to use that.

raghu
Oct 15 '08 #2
i didnt understand what u said.can u redefine the entire code and post it.thank u
Oct 15 '08 #3
gpraghuram
1,275 Expert 1GB
i didnt understand what u said.can u redefine the entire code and post it.thank u

If you want to sort the map in a different way using index my previous idea would work.
Since you want to sort by value then you should use a different map making the value as the index.


raghu
Oct 15 '08 #4
sicarie
4,677 Expert Mod 4TB
i didnt understand what u said.can u redefine the entire code and post it.thank u
Per the Posting Guidelines of this site, nobody is going to do your work for you. Please make an attempt at the suggestion, or ask a more specific question about what you do not understand.
Oct 15 '08 #5

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