I'm not quite sure what you're asking. Do you want to convert a string formatted as x,y to two integers and make a point object out of that? If so you can use stringstream to parse the input into ints:
Code:
#include <iostream>
#include <string>
#include <sstream>

using namespace std;

struct point {
  int x;
  int y;

  point()
    : x ( 0 )
    , y ( 0 )
  {}
  point ( int x, int y )
    : x ( x )
    , y ( y )
  {}
};

int main()
{
  string s ( "12,36" );
  istringstream iss ( s );
  int new_x;
  int new_y;

  iss>> new_x;
  iss.ignore();
  iss>> new_y;

  point new_point ( new_x, new_y );

  cout<< new_point.x <<' '<< new_point.y;
}