请教高人指导:C语言及数据结构题?小弟在此先谢过!

Question

#include<stdio.h>
#include<stdlib.h>
typedef int datatype;
typedef struct node
{
datatype data;
struct node *lchild;
struct node *rchild;
}BINTNODE;
typdedef BINTNODE *BINTREE;
void createbintree(BINTREE *t)
{
int a;
scanf("%d",&a);
if(a==0)
*t=NULL;
else
{
*t=(BINTNODE *)malloc(sizeof(BINTNODE));
(*t)->data=a;
createbintree(&(*t)->lchild);
createbintree(&(*t)->rchild);
}
}
void preorder(BINTREE T)
{
if(T)
{
printf("%d",T->data);
preorder(T->lchild);
preorder(T->rchild);
}
}
main()
{
BINTREE t=NULL;
printf("\n please input nodes of BINTREE:");
createbintree(&t);
printf("the preorder is:");
preorder(t);
}
请问最后一个t的值从那儿来呀?又是什么?
preorder(t); 这个t的值是多少呀?从那儿来的呀?

Answer 1

createbintree(&t);//建树
preorder(t);//打印刚刚建的树
BINTREE t=NULL;//定义树指针