帮忙看一下c++代码，帮助改正

#include <iostream>
#include <string>
#include <algorithm>
const int MaxSize =100;
template<class string>
struct Node
{
string data;
index next;
};
template<class string>
class List
{
private:
Node<string>str_List[MaxSize];
index avaliable,last_used,head;
public:
List();//构造函数
int new_node(); //返回链表的数据载体（数组）的可用index，如果链表已满则返回-1
};
template<class string>
int List<string>::new_node()
{
index new_index;
if (avaliable!=-1)
{
new_index = avaliable;
avaliable = str_List[avaliable].next;
}
else if (last_used < MaxSize-1)
{
new_index = ++last_used;
}
else return -1;
str_List[new_index].next = -1;
return new_index;
}
template<class string>
List<string>::List()
{

str_List[0].next = -1;