// file: lecture_21/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 = 27.272788;;

  // how great is fprintf()
  //
  //  float sum1 = 27.0;
  //  float sum2 = 99.0;
  //  fprintf(stdout, "arg 1 = %10.4f %\n", sum1);

  // 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]);
    return(1);
  }

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

  // close the file
  //
  if (fp != (FILE*)NULL) {
    fclose(fp);
  }

  /*
  // open the file for reading
  //
  /*
  FILE* fp_r = fopen(argv[1], "r");
  fprintf(stdout, "start file position = %d\n", ftell(fp_r));
  fseek(fp_r, (long)0, SEEK_END);
  fprintf(stdout, "end file position = %d\n", ftell(fp_r));
  rewind(fp_r);
  fprintf(stdout, "start file position = %d\n", ftell(fp_r));
  fclose(fp_r);
  */
  /*
  // read the data
  //
  char b1[99], b2[99], b3[99];
  float sum_2 = 0.0;
  fprintf(stdout, "BEFORE: the value of sum_2 is %10.4f\n", sum_2);
  FILE* fp_r = fopen(argv[1], "r");
  fscanf(fp_r, "%s%s%f", b1, b2, &sum_2);
  //fscanf(stdin, "%s%s%f", b1, b2, &sum_2);
  fprintf(stdout, "AFTER: the value of sum_2 is (%s) (%s) %10.4f\n",
  b1, b2,sum_2);

  fscanf(fp_r, "%*s%*s%f", &sum_2);
  fprintf(stdout, "AFTER SECOND READ: the value of sum_2 is %10.4f\n", sum_2);
  fprintf(stdout, "new file position = %d\n", ftell(fp_r));
  fclose(fp_r);

  /*
  // 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
  //
  FILE* 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);
  */
  
  /*
  // open a file for reading
  //
  FILE* fp_r = fopen(argv[1], "r");
  char tmp[999];
  fgets(tmp, 999, fp_r);
  fprintf(stdout, "first line: [%s]", tmp);
  fgets(tmp, 999, fp_r);
  fprintf(stdout, "second line: [%s]", tmp);
  */
	
  /*
  // read an array
  //
  long N = 3;
  float a[N];
  fscanf(fp_r, "%f%f%f", &a[0], &a[1], &a[2]);

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

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

  // exit gracefully
  //
  return 0;
}