二叉树的非递归前序遍历

#include <stdlib.h>
#include <stdio.h>
#define ElemType char
typedef struct BiTNode *BiTree;
struct BiTNode{
    ElemType data;
    BiTree lchild,rchild;
};

typedef struct STACKnode* link;
struct STACKnode{
	BiTree item ;
	link next;
};

static link head ;
link NEW(BiTree item, link next){
	link x = (link) malloc(sizeof *x);
	x->item = item;
	x->next = next;
	return x;
}

void STACKinit(int maxN){
	head = NULL;
}

int STACKempty(){
	return head == NULL;
} 

void  STACKpush(BiTree item){
	head = NEW(item,head); 
}

BiTree STACKpop(){
	BiTree item = head->item;
	link t = head->next;
	free(head);
	head = t;
	return item; 
}

BiTree CreateBiTree(){
    ElemType ch;
    BiTree T;
    scanf("%c",&ch);
    if(ch=='#')T=NULL;
    else{
        T = (BiTree)malloc(sizeof *T);
        T->data = ch;
        T->lchild = CreateBiTree();
        T->rchild = CreateBiTree();
    }
    return T;
}


void PreOrderTraverse(BiTree T){
		STACKinit(10);
		STACKpush(T);
		while(!STACKempty()){
			T = STACKpop();
			printf("%c",T->data);
			if(T->rchild != NULL)STACKpush(T->rchild);
			if(T->lchild != NULL)STACKpush(T->lchild);
		} 
}
 
 main(){
    BiTree T;
    T = CreateBiTree();
    PreOrderTraverse(T);
	// EDBA##C###HF#G###
}

运行结果