定义一个主函数main来测试单链表里面头插法createlistf，尾插法createlistr，查找locateelem，插入listinsert，删除listdelete

在大多数编程语言中，特别是像C++这样的命令行应用程序中，你可以创建一个名为`main`的函数作为程序的入口点来测试链表的各种操作。这里是一个简化的示例，展示了如何使用`main`函数来测试你提到的链表操作：

#include <iostream>
using namespace std;

// 定义链表节点结构体和相应的函数
struct ListNode {
    int data;
    ListNode* next;
};

ListNode* createlistf(int first); // 头插法创建链表
ListNode* createlistr(int last);   // 尾插法创建链表
bool locateelem(ListNode* head, int value); // 查找元素
void listinsert(ListNode*& head, int value); // 在链表中插入元素
ListNode* listdelete(ListNode*& head, int value); // 删除链表中的元素

int main() {
    // 初始化链表
    ListNode* head = nullptr;
    
    // 测试头插法
    cout << "Testing createListF with value 1:\n";
    head = createlistf(1);
    if (head) {
        cout << "Head of the created list: " << head->data << endl;
    } else {
        cout << "Failed to create the list." << endl;
    }
    
    // 测试尾插法
    cout << "\nTesting createListR with value 2:\n";
    ListNode* tail = createlistr(2);
    if (tail && tail->next == nullptr) {
        cout << "Tail of the created list: " << tail->data << endl;
    } else {
        cout << "Failed to create the list or append element." << endl;
    }

    // 测试其他功能
    cout << "\nInserting value 3 at the beginning:\n";
    listinsert(head, 3);
    if (locateelem(head, 3)) {
        cout << "Element 3 is present in the list.\n";
    } else {
        cout << "Element 3 not found after insertion.\n";
    }

    // 然后尝试删除元素
    cout << "\nDeleting value 2 from the list:\n";
    head = listdelete(head, 2);
    if (locateelem(head, 2)) {
        cout << "Value 2 should have been deleted but found.\n";
    } else {
        cout << "Value 2 successfully deleted.\n";
    }

    return 0; // 结束main函数
}