Basic operation in Linked List 1

#include <iostream>

using namespace std;
struct node
{
    int data;
    node *next;
};
void createList(node *&head, node*& tail, int item)
{
    node* newNode = new node;
    newNode->next = NULL;
    newNode->data = item;
    if(head == NULL)
    {
        head = tail = newNode;
    }
    else
    {
        tail->next = newNode;
        tail = newNode;
    }
}
int deleteList(node *&head)    //Start Function ( Delete all item in list )
{
    node *temp;
    node *curr = new node;
    while(curr != NULL)
    {
        if(curr->data %2==1)
        {
            while(head != NULL)
            {
                temp = head;
                head = head->next;
                delete temp;
                break;
            }
        }
        curr = curr->next;
        cout<<"delete sec\n";
    }
}

int display(node *&head)
{
    node *temp = head;
    node *prev = new node;
    node *curr = new node;
    curr = head;
    int temppos = 0,pos1 = 3,pos2 = 5;
    if(temp == NULL)
    {
        cout<<"Please Enter some data to increment it \n";
        return 0;
    }
    while(curr->next != NULL && temppos != pos1)
    {
        prev = curr;
        curr = curr->next;
        temppos++;
    }
    prev->data+=20;
    cout<<"3rd position is increment it : "<<prev->data<<endl;
    while(curr->next != NULL && temppos != pos2)
    {
        prev = curr;
        curr = curr->next;
        temppos++;
    }
    prev->data+=20;
    cout<<"5d position is increment it : "<<prev->data<<endl;
    while(temp != NULL)
    {
        cout<<"data is : "<<temp->data<<endl;
        temp = temp->next;
    }
}
int main()
{
    node *tail,*head;
    head = tail = NULL;
    int choice,item;
    do
    {
        cout<<"1 - create list \n";
        cout<<"2 - inc by 20 the 3th and 5th\n";
        cout<<"4 - exit\n";
        cout<<"Enter your choice : ";cin>>choice;
        switch(choice)
        {
        case 1:
            for(int i=0;i<7;i++)
            {
                cout<<"Enter item : ";
                cin>>item;
                createList(head,tail,item);
            }
            break;
        case 2:
            display(head);
            break;
        default:
            cout<<"\n\n\n\t\t\tBYE BYE\n\n";
        }
    }
    while(choice != 4);
    return 0;
}