我的代码停在中间，没有错误C

案例1工作正常，但情况2和3只需停止循环和程序 此后，我无法选择其他情况！我想知道为什么它阻止循环进行，因为这里的选择永远不会等于0，这是我相信这是阻止循环前进的唯一原因！提前致谢。

我还检查了功能，所有这些功能对我来说似乎都很好，我不确定问题是否可能与之有关

#include "stdafx.h"
#include <iostream>
using namespace std;
void insert_node(int new_data);
void print_node();
void delete_node();
int new_data;
char choice;
struct node {
    int data;
    node* next;
};
node* head = NULL;
void main()
{
    do
    {
        cout << "Enter 1 to insert a new node n";
        cout << "Enter 2 to disply the list n";
        cout << "Enter 3 to delete the last node n";
        cin >> choice;
        switch (choice)
        {
        case '1':
            cout << "Enter the data n";
            cin >> new_data;
            insert_node(new_data);
            break;
        case '2':
            if (head != NULL)
                print_node();
            else
                cout << "SORRY, your list is empty n";
            break;
        case '3':
            delete_node();
            break;
        default:
            cout << "Invalid entry n";
        }
    } while (choice != '0');
}
void insert_node(int new_data)
{
    node* NewNode = new node;
    NewNode->data = new_data;
    if (head == NULL)
        head = NewNode;
    else
    {
        NewNode->next = head;
        head = NewNode;
    }
}
void print_node()
{
    node* printer=head;
    do
    {
        cout << printer->data<<" - ";
        printer = printer->next;
    } while (printer != NULL);
}
void delete_node()
{
    if (head == NULL)
        cout << "no node to be deleted n";
    else
    {
        node* curr = head;
        node* prev = NULL;
        while (curr->next != NULL)
        {
            prev = curr;
            curr = curr->next;
        }
        if (prev == NULL)
        {
            delete(curr);
            head = NULL;
            return;
        }
        prev->next = NULL;
        delete(curr);
    }
}