#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
#define NULL 0
#define LEN sizeof(node)
typedef int elemtype;
struct node
{
    elemtype data;
    struct node*next;
};
struct node*Createlist()
{
    node*head=NULL,*p=NULL,*r=NULL;
    head=(node*)malloc(LEN);
    r=head;
    cout<<"请输入链表的长度:"<<endl;
    int n,temp;
    cin>>n;
    cout<<"请按顺序输入链表元素："<<endl;
    for(int i=0;i<n;i++)
    {
        p=(node*)malloc(LEN);
        cin>>temp;
        p->data=temp;
        r->next=p->next;
        r=p;
    }
    return (head);
}
void Traverser(struct node*head)
{
    if(head->next==NULL)
    {
        cout<<"Error!"<<endl;
        exit(1);
    }
    else
    {
        node*r=head->next;
        while(r!=NULL)
        {
            cout<<r->data<<" ";
            r=r->next;
        }
    }
}
int IsEmpty(struct node*head)
{
    if(head->next==NULL)
        return 1;
    else
        return 0;
}
void Mergelist(node*La,node*Lb,node*Lc)
{
    node*pa=NULL,*pb=NULL,*pc=NULL;
    Lc=pc=La;
    while(pa&&pb)
    {
        if(pa->data<=pb->data)
        {
            pc->next=pa;
            pc=pa;
            pa=pa->next;
        }
        else
        {
            pc->next=pb;
            pc=pb;
            pb=pb->next;
        }
    }
        pc->next=pa?pa:pb;
        free(Lb);
}
void main()
{
    struct node*La=NULL,*Lb=NULL,*Lc=NULL,*p;
    La=Createlist();
    Lb=Createlist();
    Mergelist(La,Lb,Lc);
    p=Lc->next;
    if(p==NULL)
    {
        cout<<"biao wei kong"<<endl;
    }
    else
    {
        while(p!=NULL)
        {
            cout<<p->data<<" ";
            p=p->next;
        }
    }
    
}
看看吧，我很无奈了，初学者，大家鼓励下，谢谢

最后那个循环是怀疑调用Createlist失败加上的