wc/src/wc.c

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

int wc(FILE* fp)
{
    char c[1];
    int word = 0, num_words = 0;
	  int fn = fileno(fp);
    while (read(fn, c, sizeof(c)) > 0) {
			// could add error checking to that read call
			// could also use getc or fgetc instead of read.
        if (*c != ' ' && *c != '\n' && *c != '\t') {
            word = 1;
        } else {
            if (word) {
              num_words++;
              word = 0;
            }
        }
    }
		num_words+=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: wc file.txt\n");
        printf("   or: cat file.txt | wc\n");
        printf("   or: wc # read from user-inputted stdin\n");
    }
    return 0;
}