// lecture_16/example.cc: binary file I/O
//
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

// define the max line length
//
#define MAX_LINE_LENGTH 999

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

  // declare a buffer
  //
  char buf[MAX_LINE_LENGTH + 1];

  // open the file
  //
  FILE* fp = fopen(argv[1], "w");

  // write a floating-point number
  //
  float sum[2] = {27.25, 27.27272850000001};
  fprintf(stdout, "(write) sum = [%f, %f]\n", sum[0], sum[1]);
  fprintf(stdout, "the number of elements written was %d\n",
	  fwrite(sum, sizeof(float), 2, fp));

  // add an integer
  //
  short int i = 9;
  fprintf(stdout, "(write) i = [%d]\n", i);
  fprintf(stdout, "the number of elements written was %d\n",
	  fwrite(&i, sizeof(short int), 1, fp));

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

  // open the file for reading
  //
  FILE* fp2 = fopen(argv[1], "r");

  // read two floating-point numbers
  //
  float jsum[2];
  fprintf(stdout, "the number of elements read was %d\n",
	  fread(jsum, sizeof(float), 2, fp2));
  fprintf(stdout, "(read) sum = [%f, %f]\n", jsum[0], jsum[1]);
  
  short int ji = 0;
  fprintf(stdout, "the number of elements read was %d\n",
	  fread(&ji, sizeof(short int), 1, fp2));
  fprintf(stdout, "(read) i = [%d]\n", ji);

  // close the file
  //
  fclose(fp2);

  // open the file for reading and seek past the first four bytes
  //
  /*
  fprintf(stdout, "-----\n");
  float sum[2];
  sum[0] = -99999;
  FILE* fp = fopen(argv[1], "r");
  int pos = ftell(fp);
  fprintf(stdout, "start position = %d\n", pos);
  fseek(fp, sizeof(float), SEEK_SET);
  fprintf(stdout, "new position = %d\n", ftell(fp));

  // read one floating-point number
  //
  fprintf(stdout, "the number of elements read was %d\n",
	  fread(sum, sizeof(float), 1, fp));
  fprintf(stdout, "(read) sum = [%f]\n", sum[0]);

  // read another floating-point number
  //
  rewind(fp);
  fprintf(stdout, "the number of elements read was %d\n",
	  fread(&sum[1], sizeof(float), 1, fp));
  fprintf(stdout, "(read) sum = [%f]\n", sum[1]);

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

  // declare a line number counter
  //
  /*
  long nbytes_read = 0;
  long line_num = 0;
  FILE* fp = fopen(argv[1], "r");

  while (fgets(buf, 999, fp) != (char*)NULL) {

    // remove the linefeed
    //
    buf[strlen(buf) - 1] = (char)NULL;

    // print the line
    //
    fprintf(stdout, "%3d: %s\n", line_num, buf);

    // convert these strings to numbers
    //
    float val1 = -1, val2 = -1, val3 = -1;
    sscanf(buf, "%f%f%f", &val1, &val2, &val3);
    fprintf(stdout, "\t=> %f %f %f\n", val1, val2, val3);

    // increment the line number
    //
    line_num++;
  }
  */

  // loop over the file
  //
  FILE* fp = fopen(argv[1], "r");
  long num_read = 0;
  int BUF_SIZE = 4;

  while ((num_read = fread(buf, sizeof(char), BUF_SIZE, fp)) > 0) {

    // print the data
    //
    fprintf(stdout, "\t=> num_read = %d [%c (%d) %c (%d)]\n", num_read,
	    buf[0], buf[0], buf[1], buf[1]);

    // clear buf
    //
    memset(buf, (int)NULL, 2);
  }

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

  /*
  for (long i = 0; i < 10; i++) {
    float val = i;
    fwrite(&val, sizeof(float), 1, fp);
  }
  
  // loop over the file
  //
  long num_read = 0;
  float newval;

  while ((num_read = fread(&newval, sizeof(char), 4, fp)) > 0) {

    // print the data
    //
    fprintf(stdout, "\t=> num_read = %d [%f]\n", num_read, newval);
  }
      
  // loop over the file
  //
  long num_read = 0;
  double newval;

  while ((num_read = fread(&newval, sizeof(char), 8, fp)) > 0) {

    // print the data
    //
    float val1 = *(float*)&newval;
    float* ptr = (float*)&newval;
    ptr++;
    fprintf(stdout, "\t=> num_read = %d [%f %f]\n", num_read, val1, *ptr);
  }
      
  // close the file
  //
  fclose(fp);
  */

  // exit gracefully
  //
  return 0;
}