如何申请C++模板类型的存储空间

#ifndef BINARYTREE
#define BINARYTREE
template <typename T>
struct TreeNode
{
    TreeNode(T a=0):data(a),lchild(0),rchild(0){}
    T data;
    TreeNode<T> *lchild,*rchild;
};
#endif

#include<iostream>
#include<vector>
using namespace std;
//-----------------------------------------------------
#include"Tree.h"
TreeNode<int> *previousVisitNode;
void flatten(TreeNode<int> *root)
{
    if(!root) return;
    TreeNode<int> *right=root->rchild;
    if(previousVisitNode!=0)
    {
        previousVisitNode->rchild=0;
        previousVisitNode->lchild=root;
    }
    previousVisitNode=root;
    flatten(root->lchild);
    flatten(right);
}
//-----------------------------------------------------
TreeNode<int>* CreatBinaryTree(vector<int> a)//建立二叉排序树
{
    if(a.empty()) return 0;
    TreeNode<int> *p,*q,*root=0;
    for(int i=0;i<a.size();i++)
    {
        if(root==0)
        {
            p=new TreeNode;//这儿
            p->data=a[i];
            p->lchild=0;p->rchild=0;
            root=p;
        }
        else
        {
            p=new TreeNode;//还有这儿
            p->data=a[i];
            p->lchild=0;p->rchild=0;
            TreeNode<int> *pre;
            while(q)
            {
                if(p->data>q->data) { pre=q;q=q->rchild; }
                else if(p->data<q->data) { pre=q;q=q->lchild; }
                else break;
            }
            if(q!=0) continue;
            if(p->data>pre->data) pre->rchild=p;
            else pre->lchild=p;
        }
        q=root;
    }
    return root;
}
int main()
{
    int a[]={5,4,3,2,1,6,7,8,9};
    vector<int> num(a,a+9);
    TreeNode<int> *r=CreatBinaryTree(num);
    flatten(r);
    for(TreeNode<int> *p=r;p;p=p->lchild)
        cout <<p->data<<" ";
    cout<<endl;
    return 0;
}