STL set with custom data type

{ This article was recently also posted to [comp.lang.c++]. -mod }

Hi,
I have structure representing a 2 dimesional point and want to store
pointers to these in STL map. I define the sorting criterion, such
that two points are considered equal if the distance between them is
negligeble (less than a tolerance):The problem is that after I've
inserted them I cannot find them anymore:

struct K2dCoords
{
     K2dCoords(void):m_x(0), m_y(0){};
     K2dCoords(double x, double y):m_x(x), m_y(y){};
     K2dCoords(const K2dCoords& rhs): m_x(rhs.m_x), m_y(rhs.m_y){};
     double getX() const {return m_x;}
     double getY() const {return m_y;}
     double m_x;
     double m_y;
};

// sorting criterion: two points are considered equal
// if the distance between them is negligeble (less than a tolerance):

struct eq
{
     bool operator() (const K2dCoords* p1, const K2dCoords* p2) const
     {
         const double tol = 0.25 / 1E3;
         return sqrt((p1->getX() - p2->getX()) * (p1->getX() - p2->getX
()) + (p1->getY() - p2->getY()) * (p1->getY() - p2->getY())) > tol;
     }
};

The problem is that after I've inserted some point in my set, I cannot
find them:

     // some initialisation data
     const double inc = 0.25;
     const double deckLength = 1.0;
     const double deckWidth = 0.48;
     double x = 0;
     double y = 0;
     const double PI = 3.1415926;
     std::set<K2dCoords*, eq> stlMap;

     // create some points and add them to my set
     while (x <= deckLength)
     {
         while (y <= deckWidth)
         {
             const double xSp = x * cos(30.0 * PI / 180.0) - y * sin
(30.0 * PI / 180.0);
             const double ySp = x * sin(30.0 * PI / 180.0) + y * cos
(30.0 * PI / 180.0);
             stlMap.insert(new K2dCoords(xSp, ySp));
             y += inc;
         }
         x += inc;
         y = 0;
     }

     // check if I've got them; the test point are created in the same
way as they were created for insertion
     x = 0;
     y = 0;
     while (x <= deckLength)
     {
         while (y <= deckWidth)
         {
             const double xSp = x * cos(30.0 * PI / 180.0) - y * sin
(30.0 * PI / 180.0);
             const double ySp = x * sin(30.0 * PI / 180.0) + y * cos
(30.0 * PI / 180.0);
             std::set<K2dCoords*, eq>::iterator it = stlMap.find(new
K2dCoords(xSp, ySp));
             if (it == stlMap.end())
             {
                 ASSERT(FALSE); // suerly this should not assert, but
it does (when x=0.25 and y=0)!!!
             }
             y += inc;
         }
         x += inc;
         y = 0;
     }

What am I doing wrong? Thanks.

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