// file: quiz_06/example.cc
//
// This program computes the sum of abs((2/i)) over a user-specified range.
// If it completes succesfully, it should write the sum to stdout.
//

// system include files
//
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc, char** argv) {

  // decode the command line arguments
  //
  FILE* fp;

  // run a loop
  //
  long i_start = atoi(argv[2]);
  long i_end = atoi(argv[3]);
  float sum = (float)0.0;
  long status = (long)0;

  for (long i = i_start; i < i_end; i++) {

    // accumulate fractions
    //
    sum += (float)2 / fabs((float)i);
    fprintf(stdout, "%ld: sum = %f\n", i, sum);

    // open a file and write the current value
    //
    if ((fp = fopen(argv[i], "w")) == (FILE*)NULL) {
      fprintf(stdout, "%s: error opening file (%s)\n", argv[0], argv[1]);
      return -1;
    }
    else {
      fprintf(fp, "%ld: sum = %f\n", i, sum);
    }
    fclose(fp);
  }

  // write the output sum
  //
  fprintf(stdout, "the sum over the range [%d,%d] = %f\n",
	  i_start, i_end, sum);

  // exit gracefully
  //
  return status;
}