wc/ww.c

#include <stdio.h>
#include <unistd.h>

int wc(FILE* fp)
{
    char c[1];
    int seen_word = 0, seen_sep_after_word = 0, num_words = 0;
	  int fn = fileno(fp);
    while (read(fn, c, sizeof(c)) > 0) {
        if (*c == '\n' || *c == ' ' || *c == '\t') {
            if (seen_word) {
                seen_sep_after_word = 1;
            }
        } else {
            seen_word = 1;
        }
        // exercise: what happens if you only track seen_sep,
        // instead of seen_sep_after_word?
        // test with: $ echo "	hello world" | ./wc
        if (seen_word && seen_sep_after_word) {
            num_words++;
            seen_sep_after_word = seen_word = 0;
        }
    }
		num_words+=seen_word;
    printf("%i\n", num_words);
    return 0;
}

int main(int argc, char** argv)
{
    if (argc == 1) {
        return wc(stdin);
    } else if (argc > 1) {
        FILE* fp = fopen(argv[1], "r");
        if (!fp) {
            perror("Could not open file");
            return 1;
        }
				return wc(fp) && fclose(fp);
    } else {
        printf("Usage: ww file.txt\n");
        printf("   or: cat file.txt | ww\n");
        printf("   or: ww # read from user-inputted stdin\n");
    }
    return 0;
}