一个高难度问题！

我是要建立一个二叉树 编译连接都没有错误 但是不能运行下去 运行到下面这个函数时就停止运行了
我把这个函数给你 然后我给出我的源代码


void BTree::CreateBTree(char *a)
{
BTree *s[80];
int top=-1;
left=NULL;
BTree *P=NULL;
int K;
istrstream ins(a);
char ch;
ins>>ch;
while(ch!='0')
{
switch(ch)
{ case '(':
top++;
s[top]=P;
K=1;
break;
case ')':
top--;
break;
case ',':
top++;
K=2;
break;
default:
P=new BTree;
P->data=ch;
P->left=P->right=NULL;
cout<<setw(2)<<P->data;
if(left==NULL) left=P;
else
{
if(K==1) s[top]->left=P;
else s[top]->right=P;
}
ins>>ch;
//delete p;
}

}

};


程序源代码#include<iostream.h>
#include<stdlib.h>
#include<iomanip.h>
#include<strstrea.h>
//template<class T>
class BTree
{

public:
char data;
BTree()
{
left=right=NULL;
}
BTree(int item,BTree*left1=NULL,BTree *right1=NULL):data(item),left(left1),right(right1)
{
}
BTree *&Left()
{
return left;
}
BTree *&Right()
{
return right;
}
void CreateBTree(char* a);

bool BTreeEmpty()
{
return left==NULL;
}
void TraverseBTree(int mark);
void Traverse(BTree *&BT, int mark);
int BTreeDepth();
int Depth(BTree *&BT);
int BTreeCount();
int Count(BTree *&BT);
int BTreeLeafCount();
int LeafCount(BTree *&BT);
void PrintBTree();
void Print(BTree *&BT);
void Clear(BTree *&BT);
~BTree();
private:
BTree* left; //左子树
BTree* right;//右子树
};

//template<class T>
void BTree::CreateBTree(char *a)
{
BTree *s[80];
int top=-1;
left=NULL;
BTree *P=NULL;
int K;
istrstream ins(a);
char ch;
ins>>ch;
while(ch!='0')
{
switch(ch)
{ case '(':
top++;
s[top]=P;
K=1;
break;
case ')':
top--;
break;
case ',':
top++;
K=2;
break;
default:
P=new BTree;
P->data=ch;
P->left=P->right=NULL;
cout<<setw(2)<<P->data;
if(left==NULL) left=P;
else
{
if(K==1) s[top]->left=P;
else s[top]->right=P;
}
ins>>ch;
//delete p;
}

}

};
//template class<T>
void BTree::TraverseBTree(int mark)
{
Traverse(left,mark);
};
//template<class T>
void BTree::Traverse(BTree *&BT, int mark)
{
if(mark==1)
{
if(BT!=NULL)
{
cout<<BT->data<<' ';
Traverse(BT->left,mark);
Traverse(BT->right,mark);
}
}
else
if(mark==2)
{
if(BT!=NULL)
{
Traverse(BT->left,mark);
cout<<BT->data<<' ';
Traverse(BT->right,mark);
}
}
else
if(mark==3)
{
if(BT!=NULL)
{
Traverse(BT->left,mark);
Traverse(BT->right,mark);
cout<<BT->data<<' ';
}

}
else
if(mark==4)
{
const MaxLength=80;
BTree *Q[MaxLength];
int front=0;
int rear=0;
BTree *P;
if(BT!=NULL)
{
rear=(rear+1)%MaxLength;
Q[rear]=BT;
}
while(front!=rear)
{
front=(front+1)%MaxLength;
P=Q[front];
cout<<P->data<<' ';
if(P->left!=NULL)
{
rear=(rear+1)%MaxLength;
Q[rear]=P->left;
}
if(P->right!=NULL)
{
rear=(rear+1)%MaxLength;
Q[rear]=P->right;

}
}

}
else
{
cout<<"mark值无效！遍历失败"<<endl;
}
};

//template class<T>
int BTree::BTreeDepth()
{
return Depth(left);
};

//template class<T>
int BTree::Depth(BTree *&BT)
{
if(BT==NULL) return 0;
else
{
int dep1=Depth(BT->left);
int dep2=Depth(BT->right);
if(dep1>dep2) return dep1+1;
else return dep2+1;
}
};
//template <class T>
int BTree::BTreeCount()
{
return Count(left);
};
//template <class T>
int BTree::Count(BTree *&BT)
{
if(BT==NULL) return 0;
else
return Count(BT->left)+Count(BT->right)+1;
};
//template<class T>

int BTree ::BTreeLeafCount()
{
return LeafCount(left);
};
//template class<T>
int BTree::LeafCount(BTree *&BT)
{
if(BT!=NULL) return 0;
else if(BT->left==NULL && BT->right==NULL) return 1;
else return LeafCount(BT->left)+LeafCount(BT->right);

};
//template class<T>
void BTree::PrintBTree()
{
Print(left);
};
//template class<T>
void BTree::Print(BTree *&BT)
{
if(BT==NULL) return;
else{
cout<<BT->data;
if(BT->left!=NULL || BT->right!=NULL)
{
if(BT->left!=NULL)
cout<<'(';
Print(BT->left);
if(BT->right!=NULL)
cout<<' ,';
if(BT->left!=NULL&&BT->right!=NULL)
cout<<')';
}

}

};
//template class<T>
BTree:: ~BTree()
{
Clear(left);
};
//template class<T>
void BTree::Clear(BTree *&BT)
{
if(BT!=NULL)
{
Clear(BT->left);
Clear(BT->right);
delete BT;
BT=NULL;
}
};
void main()
{
cout<<"运行结果:"<<endl;
int n;
char b[80]="(a)(b),c(d),e(f),g(h),i(j),k(l),m(n),0";
BTree B;
cout<<"创建二叉树:"<<endl;
B.CreateBTree(b);
cout<<endl;
if(!B.BTreeEmpty ())
cout<<"二叉树非空"<<endl;
else
cout<<"二叉树空"<<endl;
cout<<"先序遍历二叉树："<<endl;
B.TraverseBTree(1); cout<<endl;
cout<<"中序遍历二叉树："<<endl;
B.TraverseBTree (2); cout<<endl;
cout<<"后序遍历二叉树："<<endl;
B.TraverseBTree (3); cout<<endl;
n=B.BTreeDepth ();
cout<<"二叉树的深度="<<n<<endl;
n=B.BTreeCount ();
cout<<"二叉树的结点数="<<n<<endl;
n=B.BTreeLeafCount ();
cout<<"二叉树所有叶子结点="<<n<<endl;
//cout<<"二叉树的广义表输出："<<endl;
// B.PrintBTree () ;
//cout<<')'<<endl;
//cin.get();


}