calc.c

#include <stdio.h>

int main() {
    double x = 0;
    double y = 0;
    double z = 0;
    char c = ' ';

    WHILE:
        printf("Enter First Number: ");
        scanf("%lf", &x);

        printf("Enter Second Number: ");
        scanf("%lf", &y);

        CHAR:
            printf("Enter calc [*,/,+,-]: ");
            scanf("%c", &c);

        switch(c){
            case '*':
                z = x * y;
                goto ANS;

            case '/':
                z = x / y;
                goto ANS;

            case '+':
                z = x + y;
                goto ANS;

            case '-':
                z = x - y;
                goto ANS;
        }
        goto CHAR;

        ANS: printf("Answer: %lf\n", z);

        ANOTHER: printf("Another? [y/n]");
        scanf("%c", &c);
        switch(c){
            case 'y':
            case 'Y':
                goto WHILE;

            case 'n':
            case 'N':
                goto EXIT;
        }

        goto ANOTHER;

    EXIT: printf("GoodBye");
    return 0;
}