course statistics

#include <float.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
static void statistics(const char *fname, const char *suffix,
                       const char *format) {
  char to_name[BUFSIZ];
  sprintf(to_name, "%s.%s", fname, suffix);
  FILE *from = fopen(fname, "r");
  FILE *to = fopen(to_name, "w");
  if (!from || !to) {
    exit(1);
  }
  int n = 0;
  double sum = 0., max = -DBL_MAX, min = DBL_MAX;
  char buf[BUFSIZ];
  while (fgets(buf, BUFSIZ, from)) {
    double e;
    if (sscanf(buf, format, &e) != 1) {
      exit(1);
    }
    ++n;
    sum += e;
    max = fmax(max, e);
    min = fmin(min, e);
  }
  fprintf(to, "%f\t%f\t%f\n", sum / n, max, min);
  fclose(from);
  fclose(to);
}
int main(void) {
  struct {
    char *suffix, *format;
  } course[] = {{"physics", "%*s%lf%*lf"}, {"chemistry", "%*s%*lf%lf"}};
  for (size_t i = 0; i < sizeof(course) / sizeof(course[0]); ++i) {
    statistics("result.dat", course[i].suffix, course[i].format);
  }
}