BinarySM search

#include <string.h>
#include <stdio.h>

unsigned long stateMachineSearch (char *text, char *string) {
    char c;
    int start, offset = 0, i = 0;
    FILE *fp = fopen (text, "rb");
    while ((c = fgetc (fp)) != EOF) {
        if (c == string[offset]) {
            if (offset == 0)
                start = i;
            if (offset == (strlen (string) - 1)) {
                fclose (fp);
                return start;
            }
            offset++;
        } else {
            offset = 0;
            start = 0;
            i++;
       }
    }
    fclose (fp);
    return -1;
}

int main (int argc, char *argv[]) {
    if (argc != 3) {
        fprintf (stderr, "USAGE: ./bitap [filename] [string]\n");
        return 1;
    } else {
        unsigned long a = stateMachineSearch (argv[1] , argv[2]);
        printf ("pos: %zd\n", a);
        return 0;
    }
}