在管理系统中，插入函数怎么写？

要用malloc函数和单链表insert，还有要怎么证明这个插入函数在整个管理系统中是正确的？求大佬解答！拜托啦！！！

插入函数

void Insert()
    {
        cout << "输入要插入的序号为" << endl;
        node* p = new node;
        cin >> p->data;
        p->next = NULL;
        cout << "输入在哪个序号前插入" << endl;
        int t;
        cin >> t;
        node* q = head->next, * o = head;//o记录q的前一个结点
        while(q)
        {
            if(q->data!=t)
            {
                o = o->next;
                q = q->next;
            }
            else
            {
                p->next = q;
                o->next = p;
                break;
            }
        }
        if(q==NULL)cout << "序号输入有误" << endl;
        else
        {
            cout << "插入后结果如下" << endl;
            for (node* p = head->next; p; p = p->next)
                cout << p->data<<'\t';
            cout << endl;
        }
    }

完整验证代码

#include<iostream>
using namespace std;
typedef struct node
{
    int data;
    node* next;
};
class List
{
private:
    node* head, * last;
public:
    List()//初始化
    {
        head = new node;
        head->next = NULL;
        last = head;
    }
    void CreateList()//链表创建
    {
        cout << "节点数" << endl;
        int n;
        cin >> n;
        cout << "输入结点序号" << endl;
        for (int i = 0; i < n; ++i)
        {
            node* p = new node;
            cin >> p->data;
            //尾插法
            last->next = p;
            last = p;
        }
        last->next = NULL;
    }
    void OutCome()
    {
        cout << "链表数据如下" << endl;
        for (node* p = head->next; p; p = p->next)
            cout << p->data << '\t';
        cout << endl;
    }
    void Insert()
    {
        cout << "输入要插入的序号为" << endl;
        node* p = new node;
        cin >> p->data;
        p->next = NULL;
        cout << "输入在哪个序号前插入" << endl;
        int t;
        cin >> t;
        node* q = head->next, * o = head;//o记录q的前一个结点
        while(q)
        {
            if(q->data!=t)
            {
                o = o->next;
                q = q->next;
            }
            else
            {
                p->next = q;
                o->next = p;
                break;
            }
        }
        if(q==NULL)cout << "序号输入有误" << endl;
        else
        {
            cout << "插入后结果如下" << endl;
            for (node* p = head->next; p; p = p->next)
                cout << p->data<<'\t';
            cout << endl;
        }
    }
};
int main()
{
    List l;
    l.CreateList();
    l.OutCome();
    l.Insert();
}

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