程序代码：

#include<stdio.h>
#include<stdlib.h>
#define TElemType char
typedef struct BiTNode{
    TElemType data;
    struct BiTNode *lchild,*rchild;
}BiTNode,*BiTree;
void CreateBiTree(BiTree *T)
{   TElemType ch;
    printf("Please enter the tree:");
    scanf("%c",&ch);
        if(ch==' ')
            *T=NULL;
        else{
           if(!(T=(BiTNode *)malloc(sizeof(BiTNode))))
                exit(-1);
           (*T)->data=ch;
          CreateBiTree((*T)->lchild);
          CreateBiTree((*T)->rchild);
        }
}
void preordertraverse(BiTree T)
{
  if(T)
  {
      printf("%c",T->data);
      preordertraverse(T->lchild);
      preordertraverse(T->rchild);
  }
}
void inordertraverse(BiTree T)
{
  if(T)
  {
    
      inordertraverse(T->lchild);
      printf("%c",T->data);
      inordertraverse(T->rchild);
  }
}
void postordertraverse(BiTree T)
{
  if(T)
  {
   
      postordertraverse(T->lchild);
      postordertraverse(T->rchild);
      printf("%c",T->data);
  }
}
void searchparent(BiTree T,TElemType e)
{
  if(T)
  {
      if(T->lchild->data==e||T->rchild->data==e)
      {  printf("%c",T->data); return;}
      searchparent(T->lchild,e);
      searchparent(T->rchild,e);
  }


}
main()
{ BiTree T;
TElemType e;

     CreateBiTree(&T);
     preordertraverse(T);
     inordertraverse(T);
     postordertraverse(T);
     searchparent(T,e);
}