线性表中插入元素

        算法2.4.写这个算法花了很长一段时间，唉，看来对线性表还是不够理解，继续努力，下面是代码

#include <iostream>
using namespace std;
#define maxsize 10
#define sizeincrement 5
typedef int elemtype;
typedef struct
{
  elemtype *elem;
  elemtype aa[maxsize];
  int length;
  int listsize;
}sqlist;
int main()
{
  sqlist *la,*newbase;
  int *p,*q;
  int i,len,pos,value;
  la=(sqlist *)malloc(maxsize *sizeof(sqlist));
  cout<<"链表a的长度"<<endl;
  cin>>len;
  cout<<"输入元素"<<endl;
  for(i=0;i<len;++i)
	  cin>>la->aa[i];
  cout<<"输入插入的元素和位置"<<endl;
  cin>>value>>pos;
  if(pos<1||pos>len)
	  cout<<"错误"<<endl;
  if(len>maxsize)
  {
	  newbase=(sqlist *)realloc(la->elem,(maxsize+sizeincrement) *sizeof(sqlist));
	  if(!newbase)
	  {cout<<"内存分配失败"<<endl;return 0;}
	  la=newbase;
  }
  la->listsize=len-1;
  q=&(la->aa[pos-1]);
  for(p=&(la->aa[la->listsize]);p>=q;--p)
  {//cout<<*(p+1)<<endl;
  //cout<<*p<<endl;
  *(p+1)=*p;}
  *q=value;
  ++la->listsize;
  for(i=0;i<=la->listsize;++i)
	  cout<<la->aa[i]<<" ";
  cout<<endl;
  return 0;
}