title: typedef - does not name a type
body: <p>i have two headers</p>
  
  <p>in header “BinTree.h":</p>
  
  <pre><code>typedef struct node {
      ElemType data;
      struct node *lchild;
      struct node *rchild;
  }BTNode;
  </code></pre>
  
  <p>in header "Queue.h"(which includes BinTree.h):</p>
  
  <pre><code>typedef BTNode* Dataype;
  </code></pre>
  
  <p>at compiling the compilor said:
       error: ‘BTNode’ does not name a type</p>
  
  <p>What's wrong?</p>