How to do this sorting of a list of class type?

[ertss]

Hi all,
I have got a list of class type that I need to do list.sort() on.
the class type is

class node_info{
public:
  node_number;
  node_gain;
}

And I have a list to store all these class types: list<node_info> node_list;
for example, initially the list of 3 elements would be like {{0,3},{1,2},{2,1}}

After the sort, i would like it to be like{{2,1},{1,2},{0,3}}
Could anyone tell me how to do this kind of trick? Would the time complexity be nlogn for this kind of sorting?

Thanks a lot

[Russco]

provide a less than operator for node_info's then use list::sort to sort them low to high and then list::reverse to sort them high to low, or alternatively write a comparison function and pass it in as an argument to list::sort. The function should compare two node_info's and return a bool.

[ertss]

Could you write a small example code showing me how to provide < operator for node_info?
Is that something called operator overload?
I will try to look up the book for that part.

[ertss]

Problem solved, thanks a lot.
I write my code like this.

#include <iostream>
#include <vector>
#include <list>
#include <algorithm>

using namespace std;
class node_info{
  friend bool operator<(const node_info&, const node_info&);
public:
  int node_number;
  int node_gain;
};

inline bool operator<(const node_info &lh, const node_info &rh){
  if(lh.node_gain<rh.node_gain)
    return 1;
  else 
    return 0;
}


int main(){
  list<node_info> gvec;
  for(int i=0; i!=10; i++){
    node_info temp;
    int temp_gain;
    temp.node_number=i;
    cin>>temp_gain;
    temp.node_gain=temp_gain;
    gvec.push_back(temp);
  }

  for(list<node_info>::iterator iter=gvec.begin();iter!=gvec.end();iter++)
    cout<<iter->node_number<<" "<<iter->node_gain<<endl;
  cout<<endl;

  gvec.sort();
  //sort(gvec.begin(), gvec.end());

  //list<node_info>::iterator iter=gvec.end();
  //cout<<"AA "<<*(--iter);

  for(list<node_info>::iterator iter=gvec.begin();iter!=gvec.end();iter++)
    cout<<iter->node_number<<" "<<iter->node_gain<<endl;

  cout<<"finished";


  return 0;
}