Error after running graph command in program

Hi,

The following is a miniscule program that I wrote on Linux to create a line graph.

Code:

int main()
{
   fstream myfile;
   myfile.open ("abc.txt");
   for  (float PUF = 0; PUF < 2000; PUF = PUF + 10)
   {
       if (PUF != 0)
       {
            float SI = 1000 / (PUF + 1000);
            myfile << PUF << " " << SI << " ";
       }   
   }
   myfile.close();
   system("graph -T X < abc.txt");
   return 0;
}

This piece of code works. A seperate window opens up and I can view my graph in that window. But on closing the window, I get the following error.

XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":0.0"
after 735 requests (735 known processed with 0 events remaining.

If I use float the following message also appears.

graph: input file terminated prematurely

Can someone tell me what I am doing wrong out here?

But that has nothing to do with your C++ program.

You'd get the same error message just by typing in manually:
graph -T X < abc.txt

Maybe it's complaining that there are an odd number of coordinates in the file?