1 template<class T>
2 void BinTree<T>::InOrder(BinTreeNode<T>*subTree){
3 //中序遍历以subTree为根的树
4     if(subTree!=NULL){//NULL是递归终止条件
5         InOrder(subTree->leftChild);//中序遍历左子树
6         cout<<subTree->data<<endl;//访问根结点
7         InOrder(subTree->rightChild);//中序遍历右子树 
8     } 
9 }