先序构造二叉树（1）

方法一：

#include <stdio.h>#include<stdlib.h>typedef struct node{int data;struct node *left;struct node *right;}BTree;BTree* createTree(BTree *tree){int temp;scanf("%d",&temp);if(temp==0)tree=NULL;else{tree=(BTree*)malloc(sizeof(BTree));if(tree==NULL)printf("error!\n");tree->data=temp;tree->left=createTree(tree->left);tree->right=createTree(tree->right);}return tree;}void outp(BTree *tree){if(tree){printf("%d\n",tree->data);outp(tree->left);outp(tree->right);}}void main(){BTree *tree;tree=createTree(tree);outp(tree);}