Menu en C

menu.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdbool.h>
#include <ctype.h>

void q(void) {
    char d;
    if(scanf("%hhd", &d)) {
        printf("Info: Scanf got %hhd\n", d);
    } else {
        printf("Error: Scanf failed");
    }
}

bool do_continue(void) {
    for(;;) {
        printf("\nDo you want to continue? [yN]: ");

        char c;
        while (scanf("%c", &c) > 0) {
            switch(tolower(c)) {
                case 'y':
                    return true;
                case 'n':
                    return false;
            }
        }
    }
}

int main(void)
{
    bool is_interactive = isatty(fileno(stdin));
    char c;

    if (is_interactive) printf("Interactive mode\n");

    while ((c = getchar()) != EOF) {
        if (isspace(c)) {
            printf("Info: Ignoring 0x%02hhx\n", c);
            continue;
        }

        scanf("%*[\t ]");

        if (is_interactive && getchar() != '\n') {
            scanf("%*[^\n]");
            scanf("%*1[\n]");
            printf("Error: Wrong value!\n");
            continue;
        }

        printf("Info: Got 0x%02hhx\n", c);

        switch(c) {
            case 'q':
                do {
                    q();
                } while(do_continue());
                break;
            case '0':
                printf("Info: Exit with zero\n");
                exit(EXIT_SUCCESS);
                break;
        }
    }
    printf("Info: Exit with EOF\n");
    exit(EXIT_SUCCESS);
}