What is the fastest way to count lines and words in a text file in ANSI C?

Question

What is the fastest way to count lines and words in a text file in pure ANSI C?

A word is terminated by a space or period. Line is terminated by \'\\n\'

Answer 1

Here is an explicit answer that counts the number of lines (extension to the number of words is trivial à la the C++ version linked to in OP). This version is buffered. Another answer suggests reading the entire file in first, which is simpler, but the below is more in line with what your C++ example does.

#include 
#include 

#define BUFSIZE 1024

int main(int argc, char** argv)
{
  int newlines = 0;
  char buf[BUFSIZE];
  FILE* file;

  if (argc != 2)
    return 1;

  file = fopen(argv[1], "r");
  while (fgets(buf, BUFSIZE, file))
  {
    if (!(strlen(buf) == BUFSIZE-1 && buf[BUFSIZE-2] != '\n'))
      newlines++;
  }

  printf("Number of lines in %s: %d\n", argv[1], newlines);

  return 0;
}

The BUFSIZE macro can be tweaked to maximize performance (since you say you want the fastest way). 1024 is simply a guess. Another possibility is probably to read the file memory mapped, but I didn't try since mmap is not ANSI C.