实现先序，中序和后序遍历的二叉树遍历程序

#include<stdio.h> #include<stdlib.h> #include<malloc.h> typedef char DataType; #include"treehead.h" typedef struct snode { BiTreeNode data2; struct snode *next; }LSNode; void StackInitiate(LSNode **head) //初始化带头结点链式堆栈 { if((*head=(LSNode *)malloc(sizeof(LSNode)))==NULL)exit(1); (*head)->next=NULL; } int StackNotEmpty(LSNode *head) //判断堆栈是否非空否,非空返回1,空返回0; { if(head->next==NULL)return 0; else return 1; } int StackPush(LSNode *head,BiTreeNode x) //把数据元素x插入链式堆栈head的栈顶作为新的栈顶 { LSNode *p; if((p=(LSNode *)malloc(sizeof(LSNode)))==NULL) { printf("内存空间不足无法插入!\n"); return 0; } p->data2=x; p->next=head->next; //新结点链入栈顶 head->next=p; //新结点成为新的栈顶 return 1; } int StackPop(LSNode *head,BiTreeNode *d) //出栈并把栈顶元素由参数d带回 { LSNode *p=head->next; if(p==NULL) { printf("堆栈已空出错!\n"); return 0; } head->next=p->next; //删除原栈顶元素 *d=p->data2; //原栈顶元素结点赋予d free(p); //释放原栈顶结点内存空间 return 1; } void StackDisplay(LSNode *head) //输出 { BiTreeNode *x; Initiate(&x); while(StackNotEmpty(head)!=0) { StackPop(head,x); printf("%c",x->data1); } } void StackDestroy(LSNode **head) //撤销动态申请空间 { LSNode *p,*p1; p=*head; while(p!=NULL) { p1=p; p=p->next; free(p1); } } void PreOrder(BiTreeNode *t,LSNode *head) //前序 { if(t->rightChild!=NULL)PreOrder(t->rightChild,head); if(t->leftChild!=NULL)PreOrder(t->leftChild,head); StackPush(head,*t); return; } void InOrder(BiTreeNode *t,LSNode *head) //中序 { if(t->rightChild!=NULL)InOrder(t->rightChild,head); StackPush(head,*t); if(t->leftChild!=NULL)InOrder(t->leftChild,head); return; } void PostOrder(BiTreeNode *t,LSNode *head) //后序 { StackPush(head,*t); if(t->rightChild!=NULL)PostOrder(t->rightChild,head); if(t->leftChild!=NULL)PostOrder(t->leftChild,head); return; } int main() { BiTreeNode *a; LSNode *head; StackInitiate(&head); a=CreatTree(); PreOrder(a,head); printf("先序遍历："); StackDisplay(head); printf("\n\n"); InOrder(a,head); printf("中序遍历："); StackDisplay(head); printf("\n\n"); PostOrder(a,head); printf("后序遍历："); StackDisplay(head); printf("\n\n"); StackDestroy(&head); Destroy(&a); return 1; }