// file: lecture_17/example.cc
//
#include <stdio.h>
#include <stdlib.h>
//#include <string.h>

// my main program starts here
//
int main(int argc, char** argv) {

  // declare local variables
  //
  float sum = 27.272727272;

  // open a file
  //
  FILE* fp = fopen(argv[1], "w");
  if (fp == (FILE*)NULL) {
    fprintf(stdout, "%s: error opening file (%s)\n", argv[0], argv[1]);
  }

  // print to the terminal as ASCII
  //
  fprintf(fp, "sum = %10.4f\n", sum);
  fprintf(fp, "%s ... %s\n", "this is a test", "another test");

  // close the file
  //
  fclose(fp);

  // open the file for reading
  //
  FILE* fp_r = fopen(argv[1], "r");
  fprintf(stdout, "file position = %d\n", ftell(fp_r));

  // read the data
  //
  char b1[99], b2[99], b3[99];
  float sum_2;
  fscanf(fp_r, "%s%s%f", b1, b2, &sum_2);
  fprintf(stdout, "the value of sum_2 is %10.4f\n", sum_2);

  // where are we in the file
  //
  fprintf(stdout, "current file position = %d\n", ftell(fp_r));

  rewind(fp_r);
  fprintf(stdout, "current file position = %d\n", ftell(fp_r));
  
  fscanf(fp_r, "%s%s%s", b1, b2, &b3);
  fprintf(stdout, "current file position = %d\n", ftell(fp_r));

  sum_2 = atof(b3);
  fprintf(stdout, "the value of sum_2 is %10.4f\n", sum_2);

  // close the file
  //
  fclose(fp_r);

  // open a file for writing
  //
  fp = fopen(argv[1], "r+");
  fseek(fp, (long)0, SEEK_END);
	
  // print an array
  //
  long N = 3;
  float a[N] = {1, 2, 3};

  for (long i = 0; i < N; i++) {
    fprintf(fp, "%10.4f ", a[i]);
  }
  fprintf(fp, "\n");

  // close the file
  //
  fclose(fp);
  
  // exit gracefully
  //
  return 0;
}