二叉树创建时的指针问题
部分源代码：
typedef char ElemType;
typedef struct node
{
ElemType data;
struct node * lchild;
struct node * rchild;
}node, *Tree;
void CreateTree( Tree tree )
{
tree = ( Tree )malloc( sizeof( struct node ) );
......
}
int main( void )
{
Tree bitree;
CreateTree( bitree );
system( "pause" );
return 0;
}
程序报错！
1."The variable bitree is being used without being initialized"
我不明白，在main函数中创建了一个指向node的指针。
在CreateTree中对其进行初始化为什么不行呢？
2.我在网上看了一些程序，
比如这个：
typedef struct treenode
{
char data;
int weight;
treenode *left;
treenode *right;
}Treenode,*Treep;
//初始化二叉树
void init_tree(Treep &root)
{
root=NULL;
}
我不明白init_tree中的形参的意思？root是什么类型的变量？Treep在这里是将它强制转换吗成Treep型吗？
好纠结啊？
[解决办法]
C语言写法
不要和C++里面的引用（&）搞混了
#include<stdio.h>
#include<stdlib.h>
typedef struct btnode{
char data;
struct btnode *lchild, *rchild;
}BTNode;
typedef struct{
BTNode elem[20];
int front,rear;
}SqQueue;
BTNode * CreatTree( void );
void Preorder(BTNode *bt );
void Inorder(BTNode *bt );
void Postorder(BTNode *bt );
void Levelsorder(BTNode *bt);
void ExChangeLeafs(BTNode *bt);
void EnQueue(SqQueue *sq,BTNode *bt);
void DelQueue(SqQueue *sq,BTNode *p);
void InitQueue(SqQueue *sq);
void Disptree(BTNode *bt);
main()
{
BTNode *t;
char s[10];
for(;;)
{
printf("1--------CreatTree 2-----------Preorder \n");
printf("3--------Inorder 4-----------Postorder \n");
printf("5--------Levelsorder 6-----------ExchangeLeafs(Preorder) \n");
printf("7--------Exit\n");
gets(s);
switch(*s)
{
case '1': t=CreatTree();
break;
case '2': Preorder(t);
printf("\n");
break;
case '3': Inorder(t);
printf("\n");
break;
case '4': Postorder(t);
printf("\n");
break;
case '5': Levelsorder(t);
printf("\n");
break;
case '6': ExChangeLeafs(t);
Disptree(t);
printf("\n");
break;
case '7': printf("exit \n");
exit(0);
}
}
}
#define MAXNUM 20
BTNode * CreatTree( void )
{ int i=1,j;char ch;
BTNode *p[MAXNUM+1],*t,*s;
t=NULL;
printf("\n enter i,ch: \n");
scanf("%d,%c",&i,&ch);
while( i!=0 && ch!='#')
{
s=(BTNode *)malloc(sizeof(BTNode));
s->data=ch;
s->lchild=s->rchild=NULL;
p[i]=s;
if(i==1) t=s;
else
{
j=i/2;
if(i%2==0) p[j]->lchild=s;
else p[j]->rchild=s;
}
scanf("%d,%c",&i,&ch);
}
ch=getchar();
return t;
}
void Preorder(BTNode *bt )
{
if (bt)
{
printf("%5c",bt->data);
Preorder(bt->lchild);
Preorder(bt->rchild);
}
}
void Inorder(BTNode *bt )
{
if (bt)
{
Inorder(bt->lchild);
printf("%5c",bt->data);
Inorder(bt->rchild);
}
}
void Postorder(BTNode *bt )
{
if (bt)
{
Postorder(bt->lchild);
Postorder(bt->rchild);
printf("%5c",bt->data);
}
}
void ExChangeLeafs(BTNode *bt)
{
BTNode *temp;
if(bt)
{
temp=bt->lchild;
bt->lchild=bt->rchild;
bt->rchild=temp;
ExChangeLeafs(bt->lchild);
ExChangeLeafs(bt->rchild);
}
}
void Levelsorder(BTNode *bt)
{
BTNode p;
SqQueue sq;
InitQueue(&sq);
EnQueue(&sq,bt);
while(sq.front!=sq.rear)
{
DelQueue(&sq,&p);
printf("%5c",p.data);
if(p.lchild) EnQueue(&sq,p.lchild);
if(p.rchild) EnQueue(&sq,p.rchild);
}
}
void InitQueue(SqQueue *sq)
{
sq->front=sq->rear=0;
}
void EnQueue(SqQueue *sq ,BTNode *bt)
{ sq->elem[sq->rear]=*bt;
sq->rear=(sq->rear+1)%20;
}
void DelQueue(SqQueue *sq,BTNode *p)
{
*p=sq->elem[sq->front];
sq->front=(sq->front+1)%20;
}
void Disptree(BTNode *bt)
{
if(bt)
{
printf("%c",bt->data);
if(bt->lchild
[解决办法]
bt->rchild)
{
printf("(");
Disptree(bt->lchild);
if(bt->rchild)
printf(",");
Disptree(bt->rchild);
printf(")");
}
}
}
#include<stdio.h>
#include<stdlib.h>
typedef struct node
{
int a;
struct node *lchild,*rchild;
}Binnode;
Binnode *Creattree()
{
Binnode *t;
int m;
scanf("%d",&m);
if(m==0) t=NULL;
else{
t=(Binnode *)malloc(sizeof(Binnode));
t->data=m;
t->lchild=Creattree();
t->rchild=Creattree();
}
return t;
}
//用中序遍历二叉树（递归算法）
void Inorder(Binnode *t)
{
if(t)
{
Inorder(t->lchild);
printf("%2d",t->data);
Inorder(t->rchild);
}
}
//求二叉树高度
int high(Binnode *t)
{
int h,lh,rh;
if(t==NULL)return 0;
else
{
lh=high(t->lchild);
rh=high(t->rchild);
h=lh>rh?lh+1:rh+1;
return h;
}
}
//求二叉树的叶子总数
int leafcount(Binnode *t,int n)
{
if(t)
{
if(t->lchild==NULL&&t->rchild==NULL) n++;
n=leafcount(t->lchild,n);
n=leafcount(t->rchild,n);
}
return n;
}
void main()
{
int n=0;
Binnode *t;
printf("input data:");
t=Creattree();
printf("\n Inorder:");
Inorder(t);
printf("\n the leaf's number:");
n=leafcount(t,0);
printf("%d",n);
printf("\n the Bintree's high:%d",high(t));
system("pause");
}
