1-11

Quest: page 21

---

• How would you test the word count program ?
• What kinds of input are most likely to uncover bugs if there are any ?

---

• the wc int can overflow. Lets pretend the wc reaches the MAX value of int lets say its a uint16: then you could count 65536. When we reach MAX_VALUE +1 it's value would be 0 again. This happens in a lot of games and everywhere else. Nowadays it's less likely but can still happen. With uint64 we have a wider range.

int overflow

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

int main() {
  u_int16_t c = 65535;
  printf("value: %d\n", c);
  c++;
  printf("value: %d\n", c);
}

word count

#include <stdio.h>

#define OUT 0
#define IN 1

int main() {
  int c, nl, nw, nc, state;
  state = OUT;
  nl = nw = nc = 0;
  while ((c = getchar()) != EOF) {
    ++nc;
    if (c == '\n') {
      ++nl;
    }
    if (c == ' ' || c == '\n' || c == '\t') {
      state = OUT;
    } else if (state == OUT) {
      state = IN;
      ++nw;
    }
  }
  printf("%d %d %d\n", nl, nw, nc);
}