Diff: hash_table.cpp

Revision:

6:c9695079521d

Parent:

0:35660d7952f7

--- a/hash_table.cpp	Tue Oct 12 15:26:32 2021 +0000
+++ b/hash_table.cpp	Fri Nov 19 22:03:25 2021 +0000
@@ -1,6 +1,6 @@
 /*
- Student Name:
- Date:
+ Student Name: Nasir Christian
+ Date: November 9
 
 =======================
 ECE 2035 Project 2-1:
@@ -126,7 +126,12 @@
 * @return The pointer to the hash table entry
 */
 static HashTableEntry* createHashTableEntry(unsigned int key, void* value) {
+    HashTableEntry* newEntry = (HashTableEntry*)malloc(sizeof(HashTableEntry));
+    newEntry->value = value;
+    newEntry->key = key;
+    newEntry->next = NULL;
 
+    return newEntry;
 }
 
 /**
@@ -140,8 +145,26 @@
 * @return The pointer to the hash table entry, or NULL if key does not exist
 */
 static HashTableEntry* findItem(HashTable* hashTable, unsigned int key) {
+   /*Checking if hashtable is empty or not*/
+   if (hashTable->num_buckets == 0) {
+    return NULL;
+  }
+  unsigned int index = hashTable->hash(key);
+  HashTableEntry* temp = hashTable->buckets[index];
+      
+      while (temp){
+        if (temp->key == key){
+               return temp;
+          }
+        temp = temp->next;
+      }
+      return NULL;
+   }
+ 
+    
+      
+       
 
-}
 
 /****************************************************************************
 * Public Interface Functions
@@ -167,7 +190,7 @@
   newTable->num_buckets = numBuckets;
   newTable->buckets = (HashTableEntry**)malloc(numBuckets*sizeof(HashTableEntry*));
 
-  // As the new buckets are empty, init each bucket as NULL.
+  // As the new buckets contain indeterminant values, init each bucket as NULL.
   unsigned int i;
   for (i=0; i<numBuckets; ++i) {
     newTable->buckets[i] = NULL;
@@ -178,21 +201,95 @@
 }
 
 void destroyHashTable(HashTable* hashTable) {
+ 
+  HashTableEntry*  temp;
 
+  if (hashTable->num_buckets == 0) {
+    printf("Hash table has to contain at least 1 bucket...\n");
+    exit(1);
+  }
+  unsigned int i;
+  for ( i = 0; i < hashTable->num_buckets; i++){
+     HashTableEntry* point = hashTable->buckets[i];
+    while(point != NULL){
+        free(point->value);
+        temp = point->next;
+        free(point);
+        point = temp;
+     }
+    }
+  free(hashTable->buckets);
+  free(hashTable);
 }
 
 void* insertItem(HashTable* hashTable, unsigned int key, void* value) {
+  void* oldval;
+  HashTableEntry* entry = findItem(hashTable,key);
+    if (entry && (entry->key == key)){
+      if(entry->value == value){
+        return NULL;
+      }
+      oldval = entry->value;
+      entry->value = value;
+      return oldval;
+    }
+    else{
+      HashTableEntry* newentry = createHashTableEntry(key,value);
+      newentry->next = hashTable->buckets[hashTable->hash(key)];
+      hashTable->buckets[hashTable->hash(key)] = newentry;
 
+      return NULL;
+    }
 }
 
 void* getItem(HashTable* hashTable, unsigned int key) {
 
+  if (hashTable->num_buckets == 0) {
+    return NULL;
+  }
+
+  HashTableEntry* me = findItem(hashTable,key);
+    if (me != NULL){
+        return me->value;
+      }
+    else{
+        return NULL;
+      } 
 }
 
 void* removeItem(HashTable* hashTable, unsigned int key) {
+  int keySpot = hashTable->hash(key);
+  HashTableEntry* itemRemove = hashTable->buckets[keySpot];
 
+  if(itemRemove && ((itemRemove->key) == key)){
+    void* oldVal = itemRemove->value;
+    hashTable->buckets[keySpot] = itemRemove->next;
+    free(itemRemove);
+    return oldVal;
+  }
+
+  if (itemRemove){
+      HashTableEntry* tracker = itemRemove;
+
+      while(itemRemove->next){
+        if (((itemRemove->next)->key) == key)
+        {
+          void* old_Val = (itemRemove->next)->value;
+          tracker = itemRemove->next;
+          itemRemove->next = (tracker->next);
+          free(tracker);
+          return old_Val;
+        }
+        itemRemove = itemRemove->next;
+      }
+  }
+  return NULL;
 }
+  
+
 
 void deleteItem(HashTable* hashTable, unsigned int key) {
-
-}
\ No newline at end of file
+  /* Remove the item from the Hash Table and then free the vlaue returned*/
+  void* remove = removeItem(hashTable,key);
+  free(remove);
+}