关于二叉树非递归遍历是指针调用的问题

#define STACK_INIT_SIZE 100
#define STACKINCREMENT  10
#include <stdio.h>
#include <stdlib.h>
typedef char TElemType;
typedef struct BiTNode
{
    TElemType data;
    struct BiTNode *lchild,*rchild;
}BiTNode,*BiTree;
typedef struct
{
    BiTree *base;
    BiTree *top;
    int stacksize;
}SqStack;
void initialStack(SqStack *s)
{
    s->base=(BiTree *)malloc(STACK_INIT_SIZE*sizeof(BiTree));
    if(!s->base) exit(0);
    s->top=s->base;
    s->stacksize=STACK_INIT_SIZE;
}
void Push(SqStack *s,BiTNode *e)
{
    if(s->top-s->base>=s->stacksize)
    {
        s->base=(BiTree *)realloc(s->base,(STACK_INIT_SIZE+STACKINCREMENT)*sizeof(BiTree));
        if(!s->base) exit(0);
        s->top=s->base+s->stacksize;
        s->stacksize+=STACKINCREMENT;
    }
    *(s->top)++=e;
}
void Pop(SqStack *s,BiTree *e)
{
    if(s->top==s->base) exit(0);
    *e=*--(s->top);
}
int GetTop(SqStack *s,BiTree *e)
{
    if(s->top==s->base) return(0);
    *e=*(s->top-1);
    return(1);
}
int StackEmpty(SqStack *s)
{
    if(s->base==s->top)
        return(1);
    else
        return(0);
}

void CreatBiTree(BiTree *T)
{
    TElemType ch;
    scanf("%c",&ch);  fflush(stdin);
    if(ch=='#')
    *T=NULL;
    else
    {
    *T=(BiTNode *)malloc(sizeof(BiTNode));
    if(!*T)
            exit(0);
    (*T)->data=ch;
    CreatBiTree(&(*T)->lchild);
    CreatBiTree(&(*T)->rchild);
    }

}

void Visit(char p)
{
    printf("%c",p);
}
void InOrderTraverse(BiTree T)
{
    SqStack S;
    BiTree p;
    initialStack(&S);
    p=T;
    while(p||!StackEmpty(&S))
    {
        if(p)
        {
            Push(&S,p);
            p=p->lchild;
        }
        else
        {
            Pop(&S,&p);
        Visit(p->data);
            p=p->rchild;
        }
    }
}
void main()
{
    BiTree *t;
    printf("jianlishu:\n");
    printf("shurijieidian:");
    CreatBiTree(t);
    printf("zhongshubianlidejieguowei:");
    InOrderTraverse(*t);
    printf("\n");
}

不理解在构建二叉树中和遍历的时候，请解释一下 详细一点