talk is cheap, show you the code ...

#include<stdio.h>
#include<stdlib.h>
 

struct tNode
{
   int data;
   struct tNode* left;
   struct tNode* right;
};
 

void MorrisTraversal(struct tNode *root)
{
  struct tNode *current,*pre;
 
  if(root == NULL)
     return; 
 
  current = root;
  while(current != NULL)
  {                 
    if(current->left == NULL)
    {
      printf(" %d ", current->data);
      current = current->right;      
    }    
    else
    {

      pre = current->left;
      while(pre->right != NULL && pre->right != current)
        pre = pre->right;
 
      if(pre->right == NULL)
      {
        pre->right = current;
        current = current->left;
      }
             
      else 
      {
        pre->right = NULL;
        printf(" %d ",current->data);
        current = current->right;      
      } 
    }
  } 
}
 
struct tNode* newtNode(int data)
{
  struct tNode* tNode = (struct tNode*)
                       malloc(sizeof(struct tNode));
  tNode->data = data;
  tNode->left = NULL;
  tNode->right = NULL;
 
  return(tNode);
}
 

int main()
{
 
  /* Constructed binary tree is
            1
          /   \
        2      3
      /  \
    4     5
  */
  struct tNode *root = newtNode(1);
  root->left        = newtNode(2);
  root->right       = newtNode(3);
  root->left->left  = newtNode(4);
  root->left->right = newtNode(5); 
 
  MorrisTraversal(root);
 
  getchar();
  return 0;
}