Consider telephone book database of N clients. Make use of a hash table implementation to quickly look up client‘s telephone number.

#include<iostream>
//////////////////////////////////////////////////////////////
// //
//   Name : Vivek S. Sharma //
// Title : Hashing with sll //
// //
// //
//////////////////////////////////////////////////////////////
using namespace std;
 struct node{
int value;
node* next;
}*HashTable[10];
class hashing{
public:

hashing(){

for(int i=0 ; i<10 ; i++){
HashTable[i]=NULL;
}
}


int HashFunction(int value){
return (value%10);
}

node* create_node(int x){
node* temp=new node;
temp->next=NULL;
temp->value=x;
return temp;
}

void display(){
for(int i=0 ; i< 10; i++){
node * temp=new node;
temp=HashTable[i];
cout<<"a["<<i<<"] : ";
while(temp !=NULL){
cout<<" ->"<<temp->value;
temp=temp->next;
}
cout<<"\n";
}
}


int searchElement(int value){
bool flag = false;
            int hash_val = HashFunction(value);
            node* entry = HashTable[hash_val];
            cout<<"\nElement found at : ";
            while (entry != NULL)
    {
                if (entry->value==value)
        {
                    cout<<hash_val<<" : "<<entry->value<<endl;
                    flag = true;
                }
                entry = entry->next;
            }
            if (!flag)
                return -1;
}

void deleteElement(int value){
int hash_val = HashFunction(value);
            node* entry = HashTable[hash_val];

            if (entry == NULL )
            {
            cout<<"No Element found ";
                return;
            }

            if(entry->value==value){
            HashTable[hash_val]=entry->next;
            return;
            }
            while ((entry->next)->value != value)
    {
                entry = entry->next;
            }
            entry->next=(entry->next)->next;


}

void insertElement(int value){
int hash_val = HashFunction(value);
           // node* prev = NULL;
            //node* entry = HashTable[hash_val];
            node* temp=new node;
            node* head=new node;
            head = create_node(value);
            temp=HashTable[hash_val];
            if (temp == NULL)
                        {

                           HashTable[hash_val] =head;
                            }
            else{
            while (temp->next != NULL)

            {
                temp = temp->next;
            }

                    temp->next =head;

            }


}
};

int main(){
int ch;
int data,search,del;
hashing h;
do{
cout<<"\nTelephone : \n1.Insert \n2.Display \n3.Search \n4.Delete \n5.Exit";
cin>>ch;
switch(ch){
case 1:cout<<"\nEnter phone no. to be inserted : ";
cin>>data;
h.insertElement(data);
break;
case 2:h.display();
break;
case 3:cout<<"\nEnter the no to be searched : ";
cin>>search;

if (h.searchElement(search) == -1)
            {
        cout<<"No element found at key ";
        continue;
            }
break;
case 4:cout<<"\nEnter the phno. to be deleted : ";
cin>>del;
h.deleteElement(del);
cout<<"Phno. Deleted"<<endl;
break;
}
}while(ch!=5);
return 0;
}