Somebody set us up the BOM!

bom.c

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

int main(int argc, char *argv[]) {

  FILE *ifp, *ofp;

  ofp = fopen("test.txt", "wb");

  if (ofp == NULL) {
    printf("Can't open output file!\n");
    exit(1);
  }

  fprintf(ofp, "This is a test\nTo see if there is a BOM.\n");
  fclose(ofp);

  ifp = fopen("test.txt", "rb");

  if (ifp == NULL) {
    printf("Can't open input file!\n");
    exit(1);
  }

  unsigned char buffer[80];

  size_t readnum = fread(buffer, sizeof(unsigned char), 80, ifp);

  for (int i = 0; i < readnum; i++) {
    int c = buffer[i];
    if (c >= ' ' && c <= 'z') {
      printf("%c", c);
    } else {
      printf("\n%#04x\n", c);
    }
  }

  fclose(ifp);

}