在C的不同行中输入字符

Question

So I'm trying to implement a stack in c. I wrote all the functions, but I have a problem with fgetc function. So here's a part of my code:

    while (1) {
    printf("Choose an option: \
            \n 1 Push \
            \n 2 Pop \
            \n 3 Top \
            \n 4 Print \
            \n 5 Exit\n");

    option = fgetc(stdin);
    opt = ctoi(option);

    while ( opt < 1 || opt > 5 ) {
        printf("Wrong entry, let's try again: \n");

        option = fgetc(stdin);
        opt = ctoi(option);
    }

    switch ( opt ) {
    case 1: push(&stack, fgetc(stdin)); break;
    case 2: pop(&stack); break;
    case 3: top(&stack); break;
    case 4: print_stack(&stack); break;
    case 5: return 0; break;
    default: printf("impossible"); break;
    }

}

ctoi is a function i wrote that converts char to int. The problem is, if i enter, for exmple:

1

and press enter, the first call of the function will ask me for input, but the second one(inside the push function call) will automatically forward '\\n' as an argument, and I would like o ignore '\\n' and ask me for an input again. Is this possible? Thanks!

Answer 1

Each time Enter is hit, a '\\n' is left in stdin. You can ignore it by #include <ctype.h> and writing

do {
    option = fgetc(stdin);
} while(isspace(option));

---

I cannot, because the second call is an argument of another function.

Well, you can also write your own function for input:

int getOption(void)
{
    int option;
    do {
        option = fgetc(stdin);
    } while(isspace(option))
    return option;
}