CareerCup

void word_count(const char line[], int *wc, int *ch, int *lines)
{
  char *str=line;
  while(*str)
  {
    (*ch)++;
    if(*str == ' ')(*wc)++;
    else if(*str == '\n')(*lines)++;
  }
}

Kind of amazed that amazon will ask such simple questions....

Even though this question is easy, it has a lot of edge cases. You should think twice when questions look simple.