Problem with accumulate

[tfityo]

You can calculate sum of elements in vector by

   vector<double> wx;
   //... some code of generating data      
   double x = 0;
   for (int i = 0; i < wx.size(); i++)
        x += wx[i];
   cerr << x << endl;

the output is

-3.2818

When I use STL function accumulate from <numeric>

   x = accumulate(wx.begin(), wx.end(), 0);
   cerr << x << endl;

I receive

0

What am I doing wrong?

EDIT:
I use gcc version 4.4.1 [gcc-4_4-branch revision 150839] (SUSE Linux)

[tfityo]

"Solved" the problem in the following way:

 x = 0; zx = accumulate(wx.begin(), wx.end(), 0);
   cerr << x << endl;

Now it produces correct output. But I don't understand why the previous approach failed.

I will be happy to hear your comments.

[Cubbi]

Your accumulate performs integer addition. Use accumulate(wx.begin(), wx.end(), 0.0); to make it floating-point.

[tfityo]

Thanks, it solved the whole problem.