二叉树
这是建表达式的二叉树 总是最后输出一个?号,也不知道问题出哪了!
我知道代码看着烦,如果有空的话帮忙看下问题出哪了,谢谢了!

C/C++ code

#include "stdafx.h"#include <stdlib.h>typedef struct bitree   /*树的结构体*/{    struct bitree *lchild;    struct bitree *rchild;    char data;}trees;typedef trees *tree;typedef struct lists  /*数据链表*/{    struct lists *next;    char data;}list;int bijiao(char k)   /*比较符号*/{    switch(k)    {        case '(':            return 1;        case ')':            return 1;        case '*':            return 8;        case '/':            return 8;        case '+':            return 7;        case '-':            return 7;        case '#':            return 0;        }    return 0;}list *data(char *a)  /*创建数据链表*/{    list *head,*node,*hand;    int i=0;    head=(list*)malloc(sizeof(list));    head->data=a[i];    head->next=NULL;    hand=head;    if(head==NULL)    {        return 0;    }    i=1;    while(i<11)    {        node=(list*)malloc(sizeof(list));        if(!node)        {            return 0;        }        node->data=a[i];        node->next=NULL;        hand->next=node;        hand=hand->next;        ++i;    }    return head;}void pushtree(tree *stack,tree *k)   /*结点进栈*/{    tree node;    if(stack==NULL)    {        (*stack)=(trees*)malloc(sizeof(trees));  /*建立空结点栈*/        node=(trees*)malloc(sizeof(trees));        node->lchild=*k;        node->rchild=NULL;        *stack=node;    }    else    {        node=(trees*)malloc(sizeof(trees));   /*结点进栈*/        node->lchild=*k;        node->rchild=*stack;        *stack=node;    }}void push(tree *stack,char k)   /*符号进栈*/{    tree node,hand=NULL;    if(k=='('||k==')'||k=='*'||k=='/'||k=='+'||k=='-')  /*字母包装成结点*/        {        node=(trees*)malloc(sizeof(trees));        node->data=k;        node->rchild=(*stack);        (*stack)=node;            }    else    {        node=(trees*)malloc(sizeof(trees));  /*运算符号进栈*/        node->data=k;        node->lchild=NULL;        node->rchild=NULL;        (*stack)=node;        }    }void init(tree *head)   /*创建运算符栈头*/{    (*head)=(trees*)malloc(sizeof(trees));    (*head)->data='#';    (*head)->lchild=NULL;    (*head)->rchild=NULL;}void subtree(tree *zimu,tree *fuhao,tree *node)  /*建立子树*/{    (*node)=(*fuhao);    (*fuhao)=(*fuhao)->rchild;    (*node)->rchild=(*zimu)->lchild;    (*zimu)=(*zimu)->rchild;    (*node)->lchild=(*zimu)->lchild;    (*zimu)=(*zimu)->rchild;}void output1(list *head)   /*输出单链表*/{    while(head!=NULL)    {        printf("%c",head->data);        head=head->next;    }}void output(tree zimu)  /*后序输出*/{    if(zimu!=NULL)    {        output(zimu->lchild);        output(zimu->rchild);        printf("%c ",zimu->data);    }}int main(){    list *head=NULL;    tree zimu=NULL,zimu1=NULL,fuhao=NULL,node=NULL;    int x,y;    char k,    a[11]={'a','*','b','/','c','*','d','-','e','+','f'};    head=data(a);  /*创建数据链表*/    output1(head);  /*输出数据链表*/;     printf("\n");    init(&fuhao);   /*创建符号栈头*/    while(head!=NULL)    {        k=head->data;        if(!(k=='('||k==')'||k=='*'||k=='/'||k=='+'||k=='-'))  /*操作字母进栈*/        {            push(&zimu1,k);  /*操作字母进栈生成结点*/            pushtree(&zimu,&zimu1);   /*结点进字母栈*/            head=head->next;    /*数据链表位移*/         }         if(k=='('||k==')'||k=='*'||k=='/'||k=='+'||k=='-')   /*运算符号进栈*/         {              x=bijiao(k);     /*返回运算符号的值*/              y=bijiao(fuhao->data);   /*返回运算符号的值*/              if(x>y)              {                   push(&fuhao,k);   /*运算符号进栈*/                   head=head->next;               }               else               {                    if(k=='(')    /*左括号进栈*/                    {                         push(&fuhao,k);                         head=head->next;                     }                     if(k==')')   /*如果当前符号是')'，退出栈中'('至')'中的所有符号*/                     {                             while(fuhao->data!='(')                         {                             subtree(&zimu,&fuhao,&node);   /*运算符号与字母生成子树*/                             pushtree(&zimu,&node);    /*子树进字母栈*/                                                      }                          fuhao=fuhao->rchild;   /*符号栈位移*/                          head=head->next;                           }                       else                       {                             subtree(&zimu,&fuhao,&node);    /*运算符号与字母生成子树*/                             pushtree(&zimu,&node);    /*子树进字母栈*/                            }                  }            }    }     while(fuhao->data!='#')  /*最后推出符号栈内的所有符号，给字母链*/       {           subtree(&zimu,&fuhao,&node);  /*运算符号与字母生成子树*/            pushtree(&zimu,&node);     /*子树进字母栈*/       }output(zimu);  /*遍历输出*/} 
 

[解决办法]
pushtree()函数里else分支少了data元素初始化