Why doesn't it exit the loop?

Question

C++ / C#

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
  ifstream in("E:\\f.txt");
  ofstream out1("E:\\h.txt"), out2("E:\\g.txt");
  if (!in)
  {
    cout << "Error" << endl;
    system("pause");
    return 0;
  }
  string s;
  s += ' ';
  while (in.peek() != EOF)
  {
    getline(in, s, '#');
  }
  string sub;
  int space = 0; 
  string::size_type len = s.size();
  for (unsigned int i = 0; i < len; i = space + 1)
  {
    space = s.find(' ',  i); 
    sub = s.substr(i, space - i);
    if (sub[0] == '-')
    {
      out1 << sub << ' ';
    }
    else
    {
      out2 << sub << ' ';
    } 
  }
  in.close();
  out1.close();
  out2.close();
  system("pause");
  return 0;
}

loops at the moment of selecting a substring, everything seems to be fine, looks for a space between numbers, selects a substring, from the beginning of the search to the space, checks the number for negativity, moves the marker to the next element after the space and starts searching from it

Answer 1

You don't check for std::npos result in space:
space = s.find(' ', i);