Antique Computer Nerding

I need a program to produce gCode for cutting rectangles starting at xstart,ystart and cutting to far side xend,yend.  I have a program that does that but the more parameters on the line in the Makefile, the easier is to make a mistake.  It would be nice to specify these as -1.56,0 and 0,2.4 instead of -1.56 0 0 2.4.  So I revised the program from:

  float xStart=atof(argv[1]);
  float yStart=atof(argv[2]);  
  float xEnd=atof(argv[3]);  
  float yEnd=atof(argv[4]); 

to:

int parsePair(char* pairString, float* x, float *y)
{
  return(sscanf(pairString, "%f,%f", x, y));
}

...

 float xStart, yStart;
  if(parsePair(argv[1], &xStart, &yStart) != 2)
    {
      printf("unable to parse %s\n", argv[1]);
      displayValidArgs();
      exit(2);
    }
  float xEnd, yEnd;
  if(parsePair(argv[2], &xEnd, &yEnd) != 2)
    {
      printf("unable to parse %s\n", argv[1]);
      displayValidArgs();
      exit(2);
    }

The Makefile command goes from:

    ./mkrectangle -1.593 0 0 2.2179 -.2 -.01 -.6 3 3 .125 rectangle.ngc -a

to:

    ./mkrectpair -1.593,0 0,2.2179 -.2 -.01 -.5 3 3 .125 rectpair.ngc -a 

A minor improvement but I may create something more complex with n pairs as vertices.