先序建立二叉树和先序遍历二叉树问题，为什么输入d##后输出为100，求指教？？？

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
#define FAILURE 0
#define ERROR -2
#define OK 1
typedef char elemtype;
typedef struct NODE
{
    elemtype data;
    struct NODE *lchild,*rchild;
}NODE,*TREE;

TREE precreateTree(TREE *t)
{
    elemtype ch;
    ch=getchar();
    if(ch=='#') *t=NULL;
    else
    {
        if(!(*t=(TREE)malloc(sizeof(NODE)))) exit(FAILURE);
        (*t)->data=ch;
        precreateTree(&((*t)->lchild));
        precreateTree(&((*t)->rchild));
    }
    return *t;
}

int pretraverseTree(TREE t)
{
    if(t)
    {
        printf("%d",t->data);
        pretraverseTree(t->lchild);
        pretraverseTree(t->rchild);
    }
    return OK;
}

void main()
{
    TREE p;
    p=(TREE)malloc(sizeof(NODE));
    p=precreateTree(&p);
    pretraverseTree(p);
    printf("\n");
}