#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

typedef unsigned char byte;

struct record
{ short int year;
  byte month, day;
  short int mintemp, avgtemp, maxtemp, maxwind; };

int compare(int y1, int m1, int d1, int y2, int m2, int d2)
{ if (y1 != y2)
    return y1 - y2;
  if (m1 != m2)
    return m1 - m2;
  return d1 - d2; }

int main()
{ FILE * fin = fopen("weather.dat", "r");
  if (fin == NULL)
  { fprintf(stderr, "Can't open file\n");
    exit(1); }
  fseek(fin, 0, SEEK_END);
  int records = ftell(fin) / sizeof(struct record);
  printf("There are %d records\n", records);
  while (1)
  { printf("Enter y m d: ");
    int y, m, d;
    scanf("%d %d %d", & y, & m, &d);
    int first = 0, last = records - 1;
    while (1)
    { if (first > last)
      { printf("not found\n");
        break; }
      int mid = (first + last) / 2;
      fseek(fin, mid * sizeof(struct record), SEEK_SET);
      struct record r;
      fread(& r, sizeof(r), 1, fin);
      int c = compare(y, m, d, r.year, r.month, r.day);
      if (c == 0)
      { printf("%d %d %d %f %f %f %f\n",
               r.year, r.month, r.day, (double)r.mintemp/10, (double)r.avgtemp/10, (double)r.maxtemp/10, (double)r.maxwind/10);
        break; }
      if (c < 0)
        last = mid - 1;
      else
        first = mid + 1; } }
  fclose(fin); }