1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <strings.h>
 4 #define MAX 100
 5 
 6 char * p;
 7 typedef struct BTree{
 8     char * str;
 9     struct BTree * lchild;
10     struct BTree * rchild;
11 }BTree;
12 
13 BTree* creat_tree(){
14     BTree* temp;
15     while(*p=='
 
 ')p++;
16     if(*p=='#'){
17         p++;
18         return NULL;
19     }
20     if(*p!=' '){
21         int i=0;
22         temp = (BTree *)malloc(sizeof(BTree));
23         temp->str[i++]=*p++;
24         temp->lchild=creat_tree();
25         temp->rchild=creat_tree();
26     }
27     return
 
 temp;
28 }
29 
30 void pre_visit(BTree* node){
31     printf("%c",node->str);
32     if(node->lchild!=NULL)pre_visit(node->lchild);
33     if(node->rchild!=NULL)pre_visit(node->rchild);
34 }
35 int main()
36 {
37     char tree[MAX];p=tree;
38     BTree * head;
39     printf("Please input the tree(use char and #)\n要求按照先序遍歷的方式輸入，加上#進行區分\n例如123# #4##5##:\n
 
");
40     //scanf("%s",tree);
41     gets(tree);
42 
43     if(*p!='\0'&&*p!=' '&&*p!='#'){
44         head=(BTree *)malloc(sizeof(BTree));
45         int i=0;
46         head->str[i++]=*p++;
47         //printf("head is %c",head->str);
48         head->lchild=creat_tree();
49         head->rchild=creat_tree();
50     }
51 
52     printf("tree is :\n");
53     pre_visit(head);
54     return 0;
55 }