search string

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, const char **argv) {
  if (argc != 3) {
    exit(1);
  }
  FILE *in = fopen(argv[1], "r");
  if (!in) {
    exit(1);
  }
  long count = 0;
  for (char buf[BUFSIZ]; fgets(buf, BUFSIZ, in);) {
    for (char *p = buf, *q; p < buf + BUFSIZ && (q = strstr(p, argv[2]));
         ++count, p = q + 1) {
      ;
    }
  }
  fclose(in);
  printf("%s is %ld.\n", argv[2], count);
}