wc/src/wc.c

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

int wc(FILE* fp)
{
    register int c;
    int word = 0, num_words = 0;
    while ((c = getc(fp)) != EOF) {
        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;
        }
        int wc_status = wc(fp);
        int fclose_status = fclose(fp);
        return (wc_status == 0) && (fclose_status == 0);
        // can't do return wc_status == 0 && fclose_status == 0;
        // because then if wc returns with -1, fclose is not called.
    } 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;
}