谁来帮我看看这个排序二叉树怎么跑不起来？

#include<iostream> using namespace std; typedef int ElemType; typedef struct TreeNode{ ElemType data; struct TreeNode *l, *r; }TreeNode, *BSTree; void insert(BSTree *ST, int data) { BSTree p; if(*ST == NULL) { p = new TreeNode; p->data = data; p->l = NULL; p->r = NULL; *ST = p; } else if(data<(*ST)->data) insert(&(*ST)->l, data); else if(data>(*ST)->data) insert(&(*ST)->r, data); } void view(BSTree *ST) { view(&(*ST)->l); cout<<(*ST)->data<<" "; view(&(*ST)->l); } int main(void) { int data; BSTree ST = NULL; for(int i=0; i<5; i++) { cin>>data; insert(&ST, data); } view(&ST); return 0; } 

我找了好久硬是没找出问题来。