C++ Tutorial/STL Algorithms Helper/negate

#include <iostream>
#include <list>
#include <functional>
#include <algorithm>
using namespace std;
int main()
{
  list<double> vals;
  for(int i=1; i<10; i++) 
      vals.push_back((double)i);
  cout << "Original contents of vals:\n";
  list<double>::iterator p = vals.begin();
  while(p != vals.end()) {
    cout << *p << " ";
    p++;
  }
  cout << endl;
 
  // use the negate function object
  p = transform(vals.begin(), vals.end(),
                vals.begin(),
                negate<double>()); // call function object
  cout << "Negated contents of vals:\n";
  p = vals.begin();
  while(p != vals.end()) {
    cout << *p << " ";
    p++;
  }
  return 0;
}