FSM - parity detector

#include <stdio.h>


int main()
{
    enum { EVEN, ODD, ERROR } state=EVEN;
    int c;
    printf("Enter stream of 0 and 1 characters. End=CTRL+Z\n");
    while ((c=getchar())!=EOF) {
        if (c=='\n') continue;
        switch (state) {
        case EVEN:
            if (c=='1') {
                state=ODD;
                puts("ODD");
            } else if (c=='0') {
                puts("EVEN");
            } else {
                puts("ERROR");
                state=ERROR;
                return 0;
            }
            break;
        case ODD:
            if (c=='1') {
                state=EVEN;
                puts("EVEN");
            } else if (c=='0') {
                puts("ODD");
            } else {
                puts("ERROR");
                state=ERROR;
                return 0;
            }
            break;
        case ERROR:
            break;
        }
    }
    return 0;
}