#include"stdio.h"
typedef struct node
{  int data[20];
   struct node *left,*right;
}ErXTree;
void insert(ErXTree *t,ErXTree *s)
{  if(t==NULL)  t=s;
   else if(s->data==t->data) return;
   else if(s->data<t->data) insert(t->left,s);
   else if(s->data>t->data) insert(t->right,s);
}
void creat(ErXTree *t)
{  int x;
   ErXTree *s;
   t=NULL;
   do{  scanf("%d",&x);
        s=(ErXTree*)malloc(sizeof(ErXTree));
        s->data=x;
        s->left=NULL;
        s->right=NULL;
        insert(t,s);
     }while(x!=0);
}
void print(ErXTree *t)
{ if(t!=NULL)
  {    printf("%d",t->dada);
       if(t->left!=NULL||t->right!=NULL)
       { printf("(");
         print(t->left);
         if(t->right!=NULL)printf(",");
         print(t->right);
         printf(")");
       }
  }
}
main()
{   ErXTree *t;
    creat(t);
    printf(t);
}  先序二叉数的建立和输出问题，有错误

[此贴子已经被作者于2005-4-1 13:36:42编辑过]

这个指针真不是好掌握的:
#include "malloc.h"
#include"stdio.h"
typedef struct node
{  int data;
   struct node *left,*right;
}ErXTree;
void insert(ErXTree **t,ErXTree *s)
{  if(*t==NULL)  *t=s;
   else if(s->data==(*t)->data) return;
   else if(s->data<(*t)->data) insert(&(*t)->left,s);
   else if(s->data>(*t)->data) insert(&(*t)->right,s);
}
void creat(ErXTree **t1)
{  int x,k=0;
   ErXTree *s,*t;
   t=NULL;
   do{  scanf("%d",&x);
        s=(ErXTree*)malloc(sizeof(ErXTree));
 s->data=x;if(k==0)*t1=s;k++;
        s->left=NULL;
        s->right=NULL;
 insert(&t,s);
     }while(x!=0);
}
void print(ErXTree *t)
{ if(t!=NULL)
  {    printf("%d",t->data);
       if(t->left!=NULL||t->right!=NULL)
       { printf("(");
         print(t->left);
         if(t->right!=NULL)printf(",");
         print(t->right);
         printf(")");
       }
  }
}
main()
{   ErXTree *t;
    creat(&t);
    print(t);
}