Lab_prog01.c

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <stdbool.h>

#define CHOICE_CREATE  1
#define CHOICE_DISPLAY 2
#define CHOICE_INSERT  3
#define CHOICE_DELETE  4
#define CHOICE_EXIT    0
/**
 * This program implements a menu driven task to get familiar with
 * Array insertion, Array deletion and displaying contents of array.
 **/
unsigned int menu() {
  unsigned int choice = CHOICE_DELETE + 1;
  while (choice > CHOICE_DELETE) {
    printf("Enter your choice:\n");
    printf("\t %u - Create Array\n", CHOICE_CREATE);
    printf("\t %u - Display Array Elements\n", CHOICE_DISPLAY);
    printf("\t %u - Insert Element at a Position\n", CHOICE_INSERT);
    printf("\t %u - Delete an Element at a Position\n", CHOICE_DELETE);
    printf("\t %u - Exit\n", CHOICE_EXIT);
    printf("\t choice: ");
    scanf("%d", &choice);
    if (choice > CHOICE_DELETE) {
      printf("ERROR: Invalid Choice\n");
    }
  }
  return choice;
}

/**
 * Create and initialize the array of integers of given size.
 * i/p: size of integer array
 * o/p: array pointer when created successfully else NULL
 * Array elements are initialize with INT_MIN (limits.h)
 **/
int *fn_create(size_t size) {
  int *arr = calloc(size, sizeof(int));
  if (arr != (int *)NULL) {
    for (size_t i=0; i<size; i++){
      *(arr+i) = INT_MIN;
    }
  }
  return arr;
}

/**
 * Display all array elements with non-zero values along with their locations
 * Location display is required because array may contain holes
 **/
void fn_display(size_t arrsize, int arr[arrsize]) {
  for (size_t i = 0; i < arrsize; i++) {
    if (arr[i] != INT_MIN) {
      printf("Element location=%zu, Element value %d\n", i, arr[i]);
    }
  }
}

/**
 * Ask user array location and element value as an integer.
 * Insert the value at the specified location only if location is empty.
 * The value INT_MIN is not permissible as this is initialized value.
 **/
bool fn_insert(size_t arrsize, int arr[arrsize]){
  size_t location;
  int    value;
  bool retval = false;
  printf("Specify the location at which value to be inserted\n");
  printf("Location should be in the range 0-%zu: ", arrsize - 1);
  scanf("%zu", &location);
  if (location >=arrsize) {
    printf("Location %zu exceeds array size %zu\n", location, arrsize);
  } else if (arr[location] != INT_MIN) {
    printf("Location %zu already occupied with value %d\n", location, arr[location]);
  } else {
    printf("Enter the value to be inserted at location %zu: ", location);
    scanf("%d", &value);
    arr[location] = value;
    retval = true;
  }
  return retval;
}

/**
 * Ask user array location at which location is to be deleted.
 * Delete the value at the specified location only if location is non-empty.
 **/
bool fn_delete(size_t arrsize, int arr[arrsize]){
  size_t location;
  bool retval = false;
  printf("Specify location (0-%zu) whose value to be deleted: ", arrsize - 1);
  scanf("%zu", &location);
  if (location >=arrsize) {
    printf("Location %zu exceeds array size %zu\n", location, arrsize);
  } else if (arr[location] == INT_MIN) {
    printf("Location %zu does not contain any value \n", location);
  } else {
    printf("The value %d at location %zu has been deleted\n", arr[location], location);
    arr[location] = INT_MIN;
    retval = true;
  }
  return retval;
}

/** Releases the memory allocated for array
 * i/p: array pointer
 **/
void fn_exit(int *arr) {
  if (arr != NULL) {
    free(arr);
  }
}
int main() {
  size_t  arrsize = 0; // Array size
  int*  array = NULL; // actual array element are stored here
  size_t choice;

  while (true) {
    choice = menu();
    switch (choice) {
      case CHOICE_CREATE:
        if (array != NULL) {
          printf("There already exists an array, with following elements\n");
          fn_display(arrsize, array);
        } else {
          printf("Please Specify the array size: ");
          scanf("%zu", &arrsize);
          array = fn_create(arrsize);
        }
        break;

      case CHOICE_DISPLAY:
        if (array == NULL) {
          printf("Array is not initialized yet. Please first create an array\n");
          continue;
        }
        fn_display(arrsize, array);
        break;

      case CHOICE_INSERT:
        if (array == NULL) {
          printf("Array is not initialized yet. Please first create an array\n");
          continue;
        }
        fn_insert(arrsize, array);
        break;

      case CHOICE_DELETE:
        if (array == NULL) {
          printf("Array is not initialized yet. Please first create an array\n");
          continue;
        }
        fn_delete(arrsize, array);
        break;

      case CHOICE_EXIT:
      default:
        fn_exit(array);
        array = NULL;
        exit(0);
        break;
    }
  }

}