数据结构哈希表程序

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <stdbool.h>



#define SIZE 20



struct DataItem {

   int data;   

   int key;

};



struct DataItem* hashArray[SIZE];

struct DataItem* dummyItem;

struct DataItem* item;



int hashCode(int key) {

   return key % SIZE;

}



struct DataItem *search(int key) {

   //get the hash

   int hashIndex = hashCode(key);  



   //move in array until an empty

   while(hashArray[hashIndex] != NULL) {



      if(hashArray[hashIndex]->key == key)

         return hashArray[hashIndex];



      //go to next cell

      ++hashIndex;



      //wrap around the table

      hashIndex %= SIZE;

   }        



   return NULL;        

}



void insert(int key,int data) {



   struct DataItem *item = (struct DataItem*) malloc(sizeof(struct DataItem));

   item->data = data;  

   item->key = key;



   //get the hash

   int hashIndex = hashCode(key);



   //move in array until an empty or deleted cell

   while(hashArray[hashIndex] != NULL && hashArray[hashIndex]->key != -1) {

      //go to next cell

      ++hashIndex;



      //wrap around the table

      hashIndex %= SIZE;

   }



   hashArray[hashIndex] = item;

}



struct DataItem* delete(struct DataItem* item) {

   int key = item->key;



   //get the hash

   int hashIndex = hashCode(key);



   //move in array until an empty

   while(hashArray[hashIndex] != NULL) {



      if(hashArray[hashIndex]->key == key) {

         struct DataItem* temp = hashArray[hashIndex];



         //assign a dummy item at deleted position

         hashArray[hashIndex] = dummyItem;

         return temp;

      }



      //go to next cell

      ++hashIndex;



      //wrap around the table

      hashIndex %= SIZE;

   }      



   return NULL;        

}



void display() {

   int i = 0;



   for(i = 0; i<SIZE; i++) {



      if(hashArray[i] != NULL)

         printf(" (%d,%d)",hashArray[i]->key,hashArray[i]->data);

      else

         printf(" ~~ ");

   }



   printf("\n");

}



int main() {

   dummyItem = (struct DataItem*) malloc(sizeof(struct DataItem));

   dummyItem->data = -1;  

   dummyItem->key = -1;



   insert(1, 20);

   insert(2, 70);

   insert(42, 80);

   insert(4, 25);

   insert(12, 44);

   insert(14, 32);

   insert(17, 11);

   insert(13, 78);

   insert(37, 97);



   display();

   item = search(37);



   if(item != NULL) {

      printf("Element found: %d\n", item->data);

   } else {

      printf("Element not found\n");

   }



   delete(item);

   item = search(37);



   if(item != NULL) {

      printf("Element found: %d\n", item->data);

   } else {

      printf("Element not found\n");

   }

}