Is it possible to use sgi hash_map in vs2005?

Is it possible to use sgi hash_map in vs2005?

• dvferretm

  The problem is that you don't overwrote the
  size_t operator( )( const Key& Key ) const;
  function. But this is needed to get a hash value that is equal for all same strings. In your case the hasvalueis calculated based on the pointer not on the value!

  
  
  

• Yuriy T

  I wrote this simple test.

  I inserted some CString* key into a hash_map, and judged if this key exists before inserting. *Why* are there so many duplicated keys in the hash_map HOW can I avoid this

  I don't want any duplicate keys.

  This is my simple code:

  #include <hash_map>
  #include <iostream>
  #include <fstream>
  #include <ctime>
  #include <atlstr.h>
  #include <vector>
  #include <algorithm>

  using namespace stdext;
  using namespace std;

  struct less_str
  {
  bool operator()(const CString* p1, const CString* p2) const
  {
  if(*p1<*p2)
  return true;
  else
  return false;
  }
  };

  typedef stdext::hash_map<const CString*,CString*, hash_compare <const CString*, less_str>> key_result_map;
  typedef std::pair<const CString*,CString*> key_result_pair;

  class ResultList
  {
  public:
  key_result_map m_HashList;
  public:
  ResultList()
  {
  }

  void Add(CString const& key, CString const& value)
  {
  if(m_HashList.find(&key)==m_HashList.end())
  m_HashList.insert(key_result_pair(new CString(key),new CString(value)));
  }

  ~ResultList()
  {
  for(key_result_map::iterator it=m_HashList.begin();
  it!=m_HashList.end();it++)
  {
  delete it->first;
  delete it->second;
  }
  }

  void Save()
  {
  vector<CString*> vs;
  vs.reserve(m_HashList.size());
  for(key_result_map::iterator it=m_HashList.begin();
  it!=m_HashList.end();it++)
  {
  vs.push_back(new CString(*(it->first)));
  }
  sort(vs.begin(),vs.end(),less_str());

  ofstream f(_T("results.txt"));
  if(!f.fail())
  {
  for(vector<CString*>::size_type i=0;i<vs.size();i++)
  {
  f<<*vs<<endl;
  delete vs;
  }
  }
  }
  };

  int main()
  {
  ResultList rl;
  srand((unsigned)time(NULL));
  for(int i=0;i<100000;i++)
  {
  int x=int(((double) rand() / (double) 1000) * 1000);
  CString str;
  str.Format(_T("%d"),x);
  rl.Add(str,str);
  }
  rl.Save();
  return 0;
  }

  
  
  

• Raviatr

  Martin Richter wrote:

  Don't include the headers for the std::hash_map inside the VS2005. Why do you want to use the SGI hash_map Read the SGI docs what to do to replace the VC2005 STL with the SGI STL!

  MS hash_map is not in the namespace std, but stdex.

  I want to try sgi hash_map because it has different interface to ms hash_map.

  I don't understand hash_map in vs2005. It doesn't use a hash function.

  
  
  

• baty

  Martin Richter wrote:

  Why do you think the hash_map in VC2005 doesn't use a hash function Sure it does! Look at the hash_compare template!

  OK, I see.

  I  just have no idea why I got duplicate items in to hash_map while I check if my_hash_map.count(item_to_insert)==0 before I insert any items in it.

  sorry I posted it twice due to the net is too slow.

  
  
  

• Tellek Liberty

  Don't include the headers for the std::hash_map inside the VS2005.

  Why do you want to use the SGI hash_map

  Read the SGI docs what to do to replace the VC2005 STL with the SGI STL!

  
  
  

• Dr.9

  Why do you think the hash_map in VC2005 doesn't use a hash function Sure it does! Look at the hash_compare template!
  
  
• Is it possible to use sgi hash_map in vs2005?