Re: STL sort with derived class

I have a derived class that extends a base class by adding a float
member. The strange part is when I use the STL sort algorithm on a
vector of derived classes, only hte float member is sorted.
For example assume a vector containg three derived class objects
called blah.
blah[0] { ... int one = 7 , int two = 5, int three =8 , float five =
1}
blah[1] { ... int one = 6 , int two = 6, int three =4 , float five =
0}
blah[2] { ... int one = 5 , int two = 7, int three =5 , float five =
3}
both the derived class and base class have a copy constructor and the
assignment operator overloaded. The derived class also overloads the
binary operators '<', '>', and '==', al of which define their return
value based only on the float member (five).
After a sort I end up with
blah[0] { ... int one = 7 , int two = 5, int three =8 , float five =
0}
blah[1] { ... int one = 6 , int two = 6, int three =4 , float five =
1}
blah[2] { ... int one = 5 , int two = 7, int three =5 , float five =
3}
But what I expect and would like is
blah[0] { ... int one = 6 , int two = 6, int three =4 , float five =
0}
blah[1] { ... int one = 7 , int two = 5, int three =8 , float five =
1}
blah[2] { ... int one = 5 , int two = 7, int three =5 , float five =
3}

I'm having a devil of a time trying to figure this out.
thank you for your time,
Markus