出现段错误， 大家帮我看一下

litao19

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

typedef struct bnode
{
  int data;
  struct bnode *left, *right;
}btree;

void creat(btree *b);
void insert(btree *b, btree *s);
void inorder(btree *b);

int main()
{
  btree *b;
  creat(b);
  inorder(b);

  return 0;
}

void insert(btree *b, btree *s)
{
  if(s == NULL) return;
  else if(b == NULL) b = s;
  else if(b->data == s->data) return;
  else if(b->data > s->data) insert(b->left, s);
  else if(b->data < s->data) insert(b->right, s);
}

void creat(btree *b)
{
  int x;
  btree *s;
  b=NULL;

  scanf("%d", &x);
  while(x != -1)
  {
    s = (btree *)malloc(sizeof(btree));
    s->data = x;
    s->left = NULL;
    s->right = NULL;
    insert(b,s);
    scanf("%d", &x);
  }
}
  
void inorder(btree *b)
{
  if(b != NULL)
  {
    inorder(b->left);
    printf("%d ", b->data);
    inorder(b->right);
  }
}

应该怎么改？

MMMIX

Post by litao19
#include <stdio.h>
应该怎么改？

关键在于，C 中参数都是传值。如果你想在被调函数中修改调用函数中某变量的值，就要把该变量的地址传进去。参考下列代码

1. 
   
2. #include <stdio.h>
   
3. #include <stdlib.h>
   
4. 
   
5. typedef struct bnode
   
6. {
   
7.     int data;
   
8.     struct bnode *left, *right;
   
9. }btree;
   
10. 
    
11. void creat(btree **b);
    
12. void insert(btree **b, btree *s);
    
13. void inorder(btree *b);
    
14. 
    
15. int main()
    
16. {
    
17.     btree *b;
    
18. 
    
19.     creat(&b);
    
20.     inorder(b);
    
21. 
    
22.     printf("\n");
    
23. 
    
24.     return 0;
    
25. }
    
26. 
    
27. void insert(btree **b, btree *s)
    
28. {
    
29.     if(s == NULL) return;
    
30.     else if(*b == NULL) *b = s;
    
31.     else if((*b)->data == s->data) return;
    
32.     else if((*b)->data > s->data) insert(&(*b)->left, s);
    
33.     else if((*b)->data < s->data) insert(&(*b)->right, s);
    
34. }
    
35. 
    
36. void creat(btree **b)
    
37. {
    
38.     int x;
    
39.     btree *s;
    
40.     *b=NULL;
    
41. 
    
42.     scanf("%d", &x);
    
43.     while(x != -1)
    
44.     {
    
45.         s = (btree *)malloc(sizeof(btree));
    
46.         s->data = x;
    
47.         s->left = NULL;
    
48.         s->right = NULL;
    
49.         insert(b,s);
    
50.         scanf("%d", &x);
    
51.     }
    
52. }
    
53. 
    
54. void inorder(btree *b)
    
55. {
    
56.     if(b != NULL)
    
57.     {
    
58.         inorder(b->left);
    
59.         printf("%d ", b->data);
    
60.         inorder(b->right);
    
61.     }
    
62. }
    

复制代码

下面是运行结果

$ ./a.out
5
1
4
3
2
-1
1 2 3 4 5
$

litao19

非常感谢，MMMIX