帮我看看这个二叉树程序为啥会出现段错误...

Posted 2023-03-19

是一个二叉树遍历的程序，输入为in.txt，输出为三个文件pre.txt mid.txt aft.txt，文件是创建好的而且属性已经改好，编译没问题，为什么一执行就出毛病...
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
typedef struct node

char data;
struct node *lchild, *rchild;
treenode;
#define treenodelen sizeof(treenode)
treenode *tree;
treenode *createtree(treenode *tree)

FILE *fp1;
char ch;
fp1=fopen("in.txt","r");
ch=fgetc(fp1);
if (ch=='*') tree=NULL;
else

tree = (treenode *)malloc(treenodelen);
tree->data = ch;
tree->lchild=createtree(tree->lchild);
tree->rchild=createtree(tree->rchild);

fclose(fp1);
return(tree);

void pre(treenode *tree)

FILE *fp2;
fp2=fopen("pre.txt","w");
if (tree==NULL) return;
else

fputc(tree->data,fp2);
pre(tree->lchild);
pre(tree->rchild);

fclose(fp2);

void mid(treenode *tree)

FILE *fp3;
fp3=fopen("mid.txt","w");
if (tree==NULL) return;
else

mid(tree->lchild);
fputc(tree->data,fp3);
mid(tree->rchild);

fclose(fp3);

void aft(treenode *tree)

FILE *fp4;
fp4=fopen("aft.txt","w");
if (tree==NULL) return;
else

aft(tree->lchild);
aft(tree->rchild);
fputc(tree->data,fp4);

fclose(fp4);

int main()

tree=createtree(tree);
if (tree)

pre(tree);
mid(tree);
aft(tree);

return 0;

参考技术A 主要的错误在于，你的文件in.txt 在每次createtree的时候，都要打开一次，而且每次读取的都是第一个字符，递归下去，就会死循环，最后引起栈的溢出。

所要做的，就是把fopen放到递归外层。
我把createtree改写了一下，增加了一个建立结点的函数：
treenode *create_node(treenode *tree,FILE *fp)

char ch;
if((int)(ch=fgetc(fp))==EOF)
return 0;
tree = (treenode *)malloc(treenodelen);
tree->data = ch;
tree->lchild=create_node(tree->lchild,fp);
tree->rchild=create_node(tree->rchild,fp);
return (tree);


treenode *createtree(treenode *tree)

FILE *fp1;
fp1=fopen("c:\\tmp\\in.txt","r");

tree=create_node(tree,fp1);
fclose(fp1);
return(tree);

输出函数，你可以依次更改：pre(tree); mid(tree); aft(tree);本回答被提问者采纳