Re: STL stable_sort sorting issue

Hello C++ Guru,
  I am using STL stable_sort to sort the vector string data using
below code.

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

bool my_comparison( string p1, string p2)
{
    //Make first string lower case
        string::iterator StringValueIterator = p1.begin();
    transform (p1.begin(),p1.end(), StringValueIterator,toupper);

    //Make second string lower case
       StringValueIterator = p2.begin();
    transform (p2.begin(),p2.end(), StringValueIterator,toupper);

       return p1 < p2;
}

int main()
{
   typedef vector<string> holder;
   holder some_holder;
   some_holder.push_back("aaa");
   some_holder.push_back("bbb");
   some_holder.push_back("AAA");
   some_holder.push_back("BBB");

   stable_sort(some_holder.begin(),some_holder.end(),my_comparison);
   holder::iterator VectIt = some_holder.begin();
   for( ; VectIt!=some_holder.end(); ++VectIt)
   {
      cout <<*VectIt<< '\n';
   }
   return 0;
}

I got below result :
aaa
AAA
bbb
BBB

When I am expecting result like below :.

AAA
aaa
BBB
bbb

Why it's giving preference to first small case why not upper
letter ?