reallybadcode.c

#define _CRT_SECURE_NO_WARNINGS // turn off SAFE COMMANDS
// ############################
// Written By: Cristian Colocho
// Date Written: March, 14, 2015
// Purpose: Loop Menu and Switch
// ############################
#include <stdio.h>
#include <stdlib.h>

int enter(int n) {
  int number;

  printf("Enter a number: ");
  scanf("%i", &number);
  return number;
}

int square(int n) {
  int square = n*n;

  printf("%i squared is %i\n", n, square);
  return n;
}

int cube(int n)   {
  int cubed = n*n*n;

  printf("%i cubed is %i\n", n, cubed);
  return n;
}

int parity(int n) {
  char *p = n % 2 ? "odd" : "even";
  printf("%i is %s\n", n, p);
  return n;
}

int quit(int n) {
  printf("Exiting\n");
  return n;
}

struct MenuFunction {
  char *text;
  int (*f)(int n);
};

int main() {
  int choice, number = 0;
  struct MenuFunction menuitems[] = {
    {"Enter a number",    enter},
    {"Square the number", square},
    {"Cube the number",   cube},
    {"Display parity",    parity},
    {"Quit",              quit}
  };
  int menucount = sizeof(menuitems) / sizeof(struct MenuFunction);

  do {
    printf("\nSelect an option: \n");
    for (int i = 0; i < menucount; i++) {
      printf("%d) %s\n", i+1, menuitems[i].text);
    }

    scanf("%d", &choice);
    if (choice < 1 || choice > menucount) {
      printf("Invalid option\n");
      continue;
    };
    number = (menuitems[choice-1].f)(number);
  } while (choice < menucount);
}