用c语言实现链表的合并

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
typedef struct List
{
    int data;
    struct List* next;
}List;
List *pAHead,*pBHead,*pCHead;
void Union( )//函数功能：归并两个已排好序的链表
{
List* pa, *pb, *pc;
pa=pAHead->next;       //pa指向表A的头节点
    pb=pBHead->next;       //pb指向表B的头节点
pCHead = pc = pAHead;
pc->next=NULL;
    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;
        }