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

#define MAXNUM 100
struct BiTreeNode;        /*二叉树中的结点*/
typedef struct BiTreeNode *PBiTreeNode;/*结点的指针类型*/

struct BiTreeNode
   
{
    char info;
    PBiTreeNode llink;
    PBiTreeNode rlink;
};

//typedef struct BiTree *PBiTree;
typedef struct BiTreeNode *BiTree;

struct SeqStack
 {
        BiTree s[MAXNUM];
        int t;
 };
 
 typedef struct SeqStack *PSeqStack;
 
  PSeqStack createEmptyStack_seq(void)
 {
     PSeqStack pastack;
     pastack = (PSeqStack)malloc(sizeof(struct SeqStack));
     if(pastack == NULL)
         printf("Out of space!!\n");
     else
          pastack->t = -1;
     return (pastack);
  }
  
  int isEmptyStack_seq(PSeqStack pastack)
 {
     return(pastack->t == -1);
 }
  
 void push_seq(PSeqStack pastack, PBiTreeNode p)
  {
    if(pastack->t >= MAXNUM -1)
    {
         printf("Overflow!\n");
     }
     else
      {
         pastack->t = pastack->t + 1;
         pastack->s[pastack->t] = p->s[pastack->t];
      }
}

 void pop_seq(PSeqStack pastack)
 {
      if(pastack->t == -1)
         printf("Underflow! \n");
    else
         pastack->t = pastack->t - 1;
  }
 
 int top_seq(PSeqStack pastack)
 {
    return(pastack->s[pastack->t]);
  }
PBiTree createTree(PBiTree bt)
{
    char ch;
    //printf("please input data:\n");
    scanf("%c",&ch);
   
    if(ch=='#')
    {
        bt=NULL;
    }
    else
    {
        bt=(BiTree)malloc(sizeof (BiTreeNode));
        if(!t)
            exit(0);
        bt->data=ch;
        bt->lchild=CreateTree(bt->lchild);
        bt->rchild=CreateTree(bt->rchild);
    }
    return t;
}
void PreOder(PBiTree bt)
{
    PSeqStack pastack;
    BiTreeNode *c;
    if(t==NULL)
        return;
    pastack=createEmptyStack_seq();
    push_seq( pastack, bt);
    while(!isEmptyStack_seq(pastack))
    {
        c=top_seq(pastack);
        pop_seq(pastack);
        if(c!=NULL)
        {
            printf("%c".c->data);
            push_seq( pastack, llink);
            push_seq( pastack, rlink);

        }
    }

}
int main()
{
    PBiTree bt=NULL;
    bt=createTree(bt);
    printf("Pre Order:\n");
    PreOder(bt);
    return 0;
}

确实有点难看，就是左右子结点啊！楼主要有耐心看啊！

有这样写程序的吗   记得边写边编译   保持在写的过程中随时可以编译  这样速度快 有错误的话就可以第一时间发现

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

#define MAX_SIZE 100

typedef struct BitreeNode
{
    char info;
    struct BitreeNode *l_link;
    struct BitreeNode *r_link;
}*BiTree;

typedef struct SeqStack
{
    BiTree s[MAX_SIZE];
    int t;
}*PSeqStack;

/*

 *

 */
PSeqStack createEmptyStack_seq (void)
{
    PSeqStack p_stack;
   
    p_stack = (PSeqStack)malloc (sizeof(struct SeqStack));

    if ( NULL == p_stack )
    {
        printf("\tOut of space!\n");
        exit(-1);
    }
    else
    {
        p_stack->t = -1;//表示以满堆栈的方式存放数据
    }

    return p_stack;
}

/*

 *

 */
bool isEmptyStack_seq ( PSeqStack p_stack )
{
    return p_stack->t == -1;
}

/*

 *

 */
void push_seq ( PSeqStack p_stack, BiTree bt )
{
    if ( p_stack->t >= MAX_SIZE-1 )
    {
        printf("\tOverflow!\n");
        exit( -1 );
    }
    ++p_stack->t;
    p_stack->s [p_stack->t] = bt;
}

/*

 *

 */
void pop_seq ( PSeqStack p_stack )
{
    if ( p_stack->t == -1 )
    {
        printf("\tUnderflow!\n");
        exit( -1 );
    }
    --p_stack->t;
}

/*

 *

 */
BiTree top_seq ( PSeqStack p_stack )
{
    if ( isEmptyStack_seq(p_stack) )
    {
        printf("\tNo data!\n");
    }

    return p_stack->s[p_stack->t];
}

/*

 *

 */
BiTree createTree ( BiTree bt )
{
    char ch;
    scanf( "%c", &ch );
    getchar();

    if ( '#' == ch )
    {
        bt = NULL;
    }
    else
    {
        bt = (BiTree) malloc (sizeof(struct BitreeNode));
        if ( NULL == bt )
        {
            exit ( -1 );
        }

        bt->info = ch;
        bt->l_link = createTree( bt->l_link );
        bt->r_link = createTree( bt->r_link );
    }

    return bt;
}

/*

 *

 */
void PreOrder ( BiTree bt )
{
    PSeqStack p_stack;
    BiTree c;

    if ( NULL == bt )
    {
        return;
    }

    p_stack = createEmptyStack_seq();
    push_seq ( p_stack, bt );

    while ( !isEmptyStack_seq(p_stack) )
    {
        c = top_seq (p_stack);
        pop_seq (p_stack);

        if ( NULL != c )
        {
            printf ("%c", c->info );
            push_seq ( p_stack, c->r_link );
            push_seq ( p_stack, c->l_link );
        }
    }
}


int main()
{
    BiTree bt = NULL;
       
    bt = createTree( bt );

    printf("\tPre Order\n");

    PreOrder( bt );

    printf("\n\n");
    return 0;
}

谢谢版主指点，

是啊  写程序 不加注释 是很悲剧的事情