Arrays - Evan Carlstrom

arrays/arrays.c

@@ -9,6 +9,7 @@ typedef struct Array {
   char **elements;  // The string elements contained in the array
 } Array;
 
+/* researching unions in C right now for stretch goal #2, looking at how the array could handle multiple data types */
 
 /************************************
  *
@@ -21,11 +22,15 @@ typedef struct Array {
  *****/
 Array *create_array (int capacity) {
   // Allocate memory for the Array struct
-
+  Array *arr = malloc(sizeof(Array));
   // Set initial values for capacity and count
-
+  /* using arrow to retrieve the structure member as per last week's questions */
+  arr->capacity = capacity;
+  arr->count = 0; /* initialize counter to 0 as normal */
   // Allocate memory for elements
+  arr->elements = calloc(capacity, sizeof(char *));
 
+  return arr;
 }
 
 
@@ -35,9 +40,9 @@ Array *create_array (int capacity) {
 void destroy_array(Array *arr) {
 
   // Free all elements
-
+  free(arr->elements);
   // Free array
-
+  free(arr);
 }
 
 /*****
@@ -47,13 +52,16 @@ void destroy_array(Array *arr) {
 void resize_array(Array *arr) {
 
   // Create a new element storage with double capacity
-
+  char **new_storage = calloc((arr->capacity * 2), sizeof(char *)); 
   // Copy elements into the new storage
-
+  for(int i = 0; i < arr->count; i++) {
+    new_storage[i] = arr->elements[i];
+  }
   // Free the old elements array (but NOT the strings they point to)
-
+  free(arr->elements);
   // Update the elements and capacity to new values
-
+  arr->elements = new_storage;
+  arr->capacity *= 2;
 }
 
 
@@ -72,8 +80,14 @@ void resize_array(Array *arr) {
 char *arr_read(Array *arr, int index) {
 
   // Throw an error if the index is greater than the current count
-
+  if(index > arr->count) {
+    fprintf(stderr, "Index out of range.\n");
+    exit(0);
+  }
   // Otherwise, return the element at the given index
+  else {
+    return arr->elements[index]; /* not sure this else is necessary, can probably just do return outside of any inner block */
+  }
 }
 
 
@@ -83,15 +97,23 @@ char *arr_read(Array *arr, int index) {
 void arr_insert(Array *arr, char *element, int index) {
 
   // Throw an error if the index is greater than the current count
-
+  if(index > arr->count) {
+    fprintf(stderr, "Index out of range!\n");
+    exit(0);
+    /* looking at how to do the above while using errno as well */
+  }
   // Resize the array if the number of elements is over capacity
-
+  if(arr->capacity == arr->count) {
+    resize_array(arr);
+  }
   // Move every element after the insert index to the right one position
-
+  for(int i = arr->count; i >= index; i--) {
+    arr->elements[i+1] = arr->elements[i]; /* shifts each elements one position right */
+  }
   // Copy the element and add it to the array
-
+  arr->elements[index] = element;
   // Increment count by 1
-
+  arr->count++;
 }
 
 /*****
@@ -101,11 +123,15 @@ void arr_append(Array *arr, char *element) {
 
   // Resize the array if the number of elements is over capacity
   // or throw an error if resize isn't implemented yet.
-
+  /* will redo this with resizing when resize_array has been completed */
+  if(arr->capacity == arr->count) {
+    fprintf(stderr, "Array is full! Please free some space.\n");
+    exit(1);
+  }
   // Copy the element and add it to the end of the array
-
+  arr->elements[arr->count] = element;
   // Increment count by 1
-
+  arr->count++;
 }
 
 /*****
@@ -117,12 +143,21 @@ void arr_append(Array *arr, char *element) {
 void arr_remove(Array *arr, char *element) {
 
   // Search for the first occurence of the element and remove it.
+  for(int i = 0; i < arr->count; i++) {
+    if(arr->elements[i] == element) {
+      arr->elements[i] = NULL;
+      free(arr->elements[i]); /* when the desired element is found, null the value and free the memory block */
+      for(int x = i; x < arr->count; x++) {
+        arr->elements[x] = arr->elements[x + 1]; /* shifts the values after target occurrence */
+      }
+    }
+  }
   // Don't forget to free its memory!
 
   // Shift over every element after the removed element to the left one position
 
   // Decrement count by 1
-
+  arr->count--;
 }