1.先序遍歷非遞歸算法
#define maxsize 100
typedef struct
{
    Bitree Elem[maxsize];
    int top;
}SqStack;

void PreOrderUnrec(Bitree t)
{
    SqStack s;
    StackInit(s);
    p=t;
    
    while (p!=null || !StackEmpty(s))
    {
        while (p!=null)             //遍歷左子樹
        {
            visite(p->data);
            push(s,p);
            p=p->lchild;       
        }//endwhile
        
        if (!StackEmpty(s))         //通過下一次循環(huán)中的內(nèi)嵌while實(shí)現(xiàn)右子樹遍歷
        {
            p=pop(s);
            p=p->rchild;        
        }//endif
                
    }//endwhile 
    
}//PreOrderUnrec