两单链表合并有关问题

#include <iostream>
#include <string>
#include <stdio.h>
#include <malloc.h>
using namespace std;

typedef int ElemType;

typedef struct LNode
{
    ElemType elem;
    struct LNode *next;
}node, *LinkNode;

int CreateList(LinkNode L);
int GetLeagth(LinkNode L);
int DisplayList(LinkNode L, int x);
int SortList(LinkNode L, int x);
int InsertList(LinkNode l);
LNode* FindNode(LinkNode l);
void CombinaList(LinkNode la, LinkNode lb, LinkNode &lc);



int CreateList(LinkNode L)
{
    int i = 0;
    LinkNode tail;
    LinkNode head;
    int x = 0;
    int k = 0;
    tail = L;    
    printf("how many number to you want to input?\n");  //有换行的话用起来会舒服一些
    scanf("%d", &x);
    for(i = 0;i < x;i++)
    {
        printf("please input the number:\n");
        head = (LinkNode)malloc(sizeof(LNode));
        scanf("%d",&k);
        head->elem = k;
        tail->next = head;    
        tail = head;
    }
    tail->next = NULL;
    return 0;

}

int GetLeagth(LinkNode L)
{
    int i = 0;
    LinkNode node;
    node = L;    
    if( node == NULL ) return 0;  //node 是一个指针，提前指针中的元素之前一定要检查指针是否为空指针
    while(node->next != NULL)
    {
        i++;
        node = (node)->next;
    }
    return i;
}

void CombinaList(LinkNode la, LinkNode lb, LinkNode &lc)//合并la与lb，生成新链表lc   lc必须使用引用，否则不会改变实参
{
    if( la == NULL ) {          //使用指针前，要考虑到指针为空的情况
        lc = lb;
        return;
    }
    if( lb == NULL ) {
        lc = la;
        return;
    }

    lc = la;
    LinkNode node = la;
    //node = lc;
    while(node->next != NULL)
    {
        node = node->next;
    }
    //node->next = lb;          //注意lb是头结点，头结点不是元素结点，所以应该去掉头结点
    node->next = lb->next;
    free(lb);                    //释放空间
    lb = NULL;

    //return 0;                    //返回值没有意义
}

int DisplayList(LinkNode L, int x)
{
    if( !L ){                      //编写链表的函数，第一点就是考虑为空的情况
        cout << " The link table is NULL" <<endl;
        return -1;
    }
    int i = 0;
    LNode *node;
    node = L;
    printf("what your input is:");
    for(i = 0;i < x;i++)
    {
        printf("%4d ", node->next->elem);     //带头结点，需从下一个开始打印， 结点之间有空格较好
        node = node->next;
    }
    printf("\n");
    return 0;
}


int main()
{
    int i = 0;
    int h = 0;
    LinkNode la = (LinkNode)malloc(sizeof(node));     //初始化一个头结点
    la->next = NULL;
    LinkNode lb = (LinkNode)malloc(sizeof(node));     //初始化一个头结点
    lb->next = NULL;
    LinkNode lc = (LinkNode)malloc(sizeof(node));     //初始化一个头结点
    lc->next = NULL;
    CreateList(la);
    CreateList(lb);
    i = GetLeagth(la);
    h = GetLeagth(lb);

    DisplayList(la,i);
    DisplayList(lb,h);

    CombinaList(la, lb, lc);
    h = GetLeagth(lc);
    printf("The length of c is: %d\n", h);  //最好有说明
    DisplayList(lc,h);
    scanf("%d", &i);
    return 0;

}