C语言编写的二叉树问题～～

[golden_softwave_001]

/*************************************************
Copyright (C), 2000-2004, ******
File name:      ALL_TREE.cpp
Author:         ZHJ
Version:        1.0
Date:			2009-9-15
Description:    根据层次构造二叉树
*************************************************/

#include		<stdio.h>
#include		<stdlib.h>
#include		<string.h>
/*************************************************
Copyright (C), 2000-2004, ******
File name:      ALL_TREE.cpp
Author:         ZHJ
Version:        1.0
Date:			2009-9-16
Description:    构造顺序栈服务于二叉树
*************************************************/

#include	<malloc.h>
//#include	"btstruct.h"
#define		MAXALLOCATION		100			//初试分配的空间大小
#define		INCREATALLOCATE		10			//空间不足时进行补充

typedef		char	ElemType;

//构造基本的二叉树

struct	binaryTree_1
{
	ElemType				elem;	//节点元素
	struct	binaryTree_1	*lchild_1,*rchild_1;
};

typedef  struct	binaryTree_1	BinaryTree_1;


typedef	 BinaryTree_1	Type;

typedef	 struct	 stackmaze
{
	int			top;			//栈顶指针
	Type		*elems;      //存放栈元素的数组
	int			MaxSize;		//栈空间的最大尺寸
}Stack;

//////////////////////////////////初始化栈结构

void	Inite_Stack(Stack	*S)
{
	S->elems = (Type *)malloc(MAXALLOCATION*sizeof(Type));
	if(!S->elems)
		exit(1);
	S->MaxSize = 0;
	S->top = 0;
}

/////////////////////////////////当空间不够用的时候，进行再次分配

void	 AnginAllow(Stack	*S)
{
	Type	*p;
	p = (Type *)realloc(S->elems,(S->MaxSize+INCREATALLOCATE)*sizeof(Type));
	if(!p)
	{
		printf("\n空间分配失败\n");
		exit(0);
	}
	S->elems = p;			//将元素重新赋值给原数组
	S->MaxSize = S->MaxSize+INCREATALLOCATE;
}

//////////////////////////////////判断栈是否为空

int		IsStackEmpty(Stack	*S)
{
	if(S->top == 0)
		return 1;
	else
		return 0;
}


////////////////////////////////////栈的压入操作

Stack *		Push_Stack(Stack	*S,Type	  *e,int temp)
{
	if(S->MaxSize == MAXALLOCATION)
		AnginAllow(S);
	else
	{
		S->top = temp;
		S->elems[S->top] = *e;
		S->MaxSize++;
	}
		return S;
}

//////////////////////////////////////栈的弹出操作

Type		Pop_Stack(Stack	*S)
{
	if(!IsStackEmpty(S))
	{
		return	S->elems[--S->top];
	}
	else
	{
		printf("\n栈已经为空\n");
		exit(0);
	}
}

void	lay_CreateTree(BinaryTree_1		*T)
{
	Stack	*S = (Stack *)malloc(sizeof(Stack));
	Inite_Stack(S);
	char	ch = NULL;		//树节点元素
	int		i = 0,j = 0,k = 0;
	printf("\nPlease input	binary tree's element:\t");
	while((ch = getchar())!='\n')
	{
		if(ch != '#')
		{
			if(i == 0)
			{
				T = (BinaryTree_1 *)malloc(sizeof(BinaryTree_1));
				Push_Stack(S,T,0);
			}
			else
			{
				if(i % 2 == 1)
				{
					k = (i -1)/2;
					S->elems[k].lchild_1 = (BinaryTree_1 *)malloc(sizeof(BinaryTree_1));
					Push_Stack(S,S->elems[k].lchild_1,i);
				}
				else
				{
					k = (i - 2)/2;
					S->elems[k].rchild_1 = (BinaryTree_1 *)malloc(sizeof(BinaryTree_1));
					Push_Stack(S,S->elems[k].rchild_1,i);
				}
			}
			S->elems[i].elem = ch;
			S->elems[i].lchild_1 = NULL;
			S->elems[i].rchild_1 = NULL;
			j = 2*i+1;
			Push_Stack(S,NULL,j);
			j = 2*i+2;
			Push_Stack(S,NULL,j);
			i++;
		}
		else
		{
			Push_Stack(S,NULL,i);
			i++;
		}
	}
}

//遍历

void	preTravel(BinaryTree_1	*T)
{
	if(T)
	{
		printf("--> %c",T->elem);
		preTravel(T->lchild_1);
		preTravel(T->rchild_1);
	}
}

int main()
{
	BinaryTree_1		*T = NULL;
	lay_CreateTree(T);
	preTravel(T);
	return 0;
}

好像是指针越界问题，请高手调试指点一下～～～～

[logiciel]

问题1：

Stack *        Push_Stack(Stack    *S,Type      *e,int temp)
{
    if(S->MaxSize == MAXALLOCATION)
        AnginAllow(S);
    else
    {
        S->top = temp;
        S->elems[S->top] = *e;  //当e为NULL时此操作非法，要改为if (e)S->elems[S->top] = *e; else memset(&S->elems[S->top], 0, sizeof(Type));
        S->MaxSize++;
    }
        return S;
}

问题2：
void lay_CreateTree(BinaryTree_1 *T)

虽然T在lay_CreateTree内部被赋值，但调用返回后T仍然是NULL。要改为以下方式才能返回新值：

void lay_CreateTree(BinaryTree_1 **T)
(*T) = (BinaryTree_1 *)malloc(sizeof(BinaryTree_1));
lay_CreateTree(&T);

[qq675927952]

void lay_CreateTree(BinaryTree_1 *T)
可以改为void lay_CreateTree(BinaryTree_1 *&T)