二叉树的遍历

#include<stdio.h>
#include<stdlib.h> 

typedef struct treenode{
	char ch;
	struct treenode* lc,*rc;
}treenode,*treelink;

//创建以treelink为根节点的数 
treelink createtree(treelink);
void preorder(treelink); //先序 
void medorder(treelink); //中序 
void postorder(treelink);//后序 

treelink createtree(treelink t)
{
	char c;
	scanf("%c",&c);
	getchar();
	if(c == '#')
	{
		t = NULL;
	}
	else
	{
		t = (treelink)malloc(sizeof(struct treenode));
		t->ch = c;
		t->lc = createtree(t->lc); //建立以t为根节点的左子树并用指针指向它 
		t->rc = createtree(t->rc);
	}
	return t;
}

//前序遍历
void preorder(treelink t)
{
	if(!t)return;
	printf("%c\t",t->ch);
	preorder(t->lc);
	preorder(t->rc);
}

//中序遍历
void medorder(treelink t)
{
	if(!t)return;
	medorder(t->lc);
	printf("%c\t",t->ch);
	medorder(t->rc);
}

//后序遍历
void postorder(treelink t)
{
	if(!t)return;
	postorder(t->lc);
	postorder(t->rc);
	printf("%c\t",t->ch);
}

int main()
{
	treelink t = NULL;
	t = createtree(t);
	printf("preorder:\n");
	preorder(t);
	printf("\n");
	printf("medorder:\n");
	medorder(t);
	printf("\n");
	printf("postorder:\n");
	postorder(t);
	return 0;
}