编程新手-C-菜单系统掉线问题

Question

I have recently begun studying C just for the fun of it and I decided to have a go at creating a menu system, but I'm having an issue with what I think is fall-through:

#include <stdio.h>

int main (void)
{

int x, y, z;

start:
printf ("Menu 1 -- Please select a number.\n");
printf ("1\n");
printf ("2\n");
printf ("Enter selection: ");
scanf ("%i", &x);
getchar();

if (x == 1) {
    x_one:
    printf ("1.\n");
    printf ("Menu 2 -- Please select a number.\n");
    printf ("1\n");
    printf ("2\n");
    printf ("3 -- Go back.\n");
    printf ("Enter selection: ");
    scanf ("%i", &y);
    getchar();

    if (y == 1) {
        y_one_one:
        printf ("1-1.\n");
        printf ("Menu 3 -- Please select a number.\n");
        printf ("1\n");
        printf ("2\n");
        printf ("3 -- Go back.\n");
        printf ("Enter selection: ");
        scanf ("%i", &z);
        getchar();

        if (z == 1 || z == 2)
            printf ("You selected %i.\n", z);

        if (z == 3)
            goto x_one;

        else if (z > 1 && z < 3)
            goto y_one_one;
    }

    if (y == 2) {
        /* mostly the same as "if (y == 1)". */
    }

    if (y == 3)
        goto start;

    else {
        printf ("Please enter a valid selection.\n");
        goto x_one;
    }
}

if (x == 2) {
    /* Mostly the same as "if (x == 1)". */
}

else if (z > 1 && z < 2)
    goto start;

return 0;
}

The issue is, once I have reached the third menu, the program will print out the string of the selected number, but instead of terminating itself it will either display the third menu or go back to the second menu, and it will do this regardless of what number I input.

I've only been studying C for about two weeks and I don't quite have a proper understanding on how nested if statements work, if I could please get an explanation of what's causing this unexpected behavior and how to correct it that would be greatly appreciated, thank you.

I am using GCC 5.1.0 through TDM-GCC-64 on Windows 10.

Answer 1

if (y == 3)
    goto start;

else {
    printf ("Please enter a valid selection.\n");
    goto x_one;

Thats where its looping back up. If y is equal to 3 you go the start, if y is not equal to 3 then go back to start.

So basically its saying go back to beginning no matter what.

Remember this executes even after you enter Z. Code keeps going down unless you redirect it.

You'll probably get comments on the form of your programming, imo its fine for a newb, you'll learn better with time and/or after getting burned.