hash_map elements deletion

From:

"lokki" <jkusniar@gmail.com>

Newsgroups:

comp.lang.c++

Date:

7 Mar 2007 01:09:02 -0800

Message-ID:

<1173258542.196718.191590@n33g2000cwc.googlegroups.com>

Hello,

can anybody tell me what's wrong with following example code?

    char *k, *v;

    k = new char[3];
    strcpy(k, "a2");

    v = new char[10];
    strcpy(v, "987654321");

    mp.insert(std::pair<const char*, const char*>(k, v));

    std::cout << "map size " << mp.size() << std::endl;

    // find
    TStringMapConstIterator i = mp.find("a1");
    if (i != mp.end())
    {
        std::cout << " found: " << i->second << std::endl;
    }
    else
    {
        std::cout << "not found" << std::endl;
    }

    // remove
    for (TStringMapIterator j = mp.begin(); j != mp.end(); j++)
    {
        delete[] (*j).first;
        delete[] (*j).second;
    }
    mp.clear();
    std::cout << "deleted" << std::endl;

I'm using gnu c++ compiler and there are few typedefs before this code
to ensure proper comparison and hash computing of const char* in
hash_map

namespace __gnu_cxx
{
      template<> struct hash<std::string>
      {
                 size_t operator()(const std::string & __s) const
                 { return __stl_hash_string(__s.c_str()); }
      };

      struct tmt_eq_str__
      {
             bool operator() (const char *a, const char *b) const
             {
                  return !strcmp(a, b);
             }
      };

}

typedef __gnu_cxx::hash_map<const char*, const char*,
__gnu_cxx::hash<const char *>, __gnu_cxx::tmt_eq_str__> TStringMap;
typedef __gnu_cxx::hash_map<const char*, const char*,
__gnu_cxx::hash<const char *>,
__gnu_cxx::tmt_eq_str__>::const_iterator TStringMapConstIterator;
typedef __gnu_cxx::hash_map<const char*, const char*,
__gnu_cxx::hash<const char *>, __gnu_cxx::tmt_eq_str__>::iterator
TStringMapIterator;

The problem is removal of the elements. Both key and value pairs were
created by new operator. That's why I assumed, that they should be
deleted before callig mp.clear() function.

Problem is that program hangs in infinite loop when deleting elements.
There wasn't such problem when compiling similar code under VC++ 8.0

Thanks in adavance