数据结构-C语言递归实现树的前中后序遍历

#include <stdio.h>
#include <stdlib.h>
typedef struct tree
{
	int number ; 
	struct tree *left  ; 
	struct tree *right ; 
}TREE;
//对树插入节点 
void insert_tree(TREE **header , int number)
{
    //创建一颗树 
	TREE *New = NULL ; 
	New = malloc(sizeof(TREE));
	if(NULL == New)
	   return ;
	//初始化树节点的值 
	New->number = number ; 
	//分别将左子树和右子树设置为空 
	New->left = NULL ; 
	New->right = NULL ; 
	TREE **link = header ; 
	TREE *cur ; 
	while(cur = *link)
	{ 
        //判断新插入的节点和之前的值之间谁大谁小
        //小的就放在左子树，大的就放到右子树 
		if(New->number < cur->number)
			//*link = cur->left ; 
			link = &(cur->left) ;
		else
			link = &(cur->right) ; 
	}
	*link = New ;
}
//打印树 
void print_tree(TREE *header , int lever)
{
	if(header == NULL)
		return ; 
	
	print_tree(header->right , lever+1);
	int i ; 
	for(i = 0 ; i < lever ; i++)
		printf("\t");
	printf("%d\n" , header->number);

	print_tree(header->left , lever+1);
}
//树的前序遍历 
void front(TREE *header)
{
	if(header == NULL)
		return ; 
	printf("%d " , header->number);
	front(header->left);
	front(header->right);
}
//树的中序遍历 
void middle(TREE *header)
{
	if(header == NULL)
		return ; 
	middle(header->left);
	printf("%d " , header->number);
	middle(header->right);
}
//树的后序遍历 
void back(TREE *header)
{
	if(header == NULL)
		return ; 
	back(header->left);
	back(header->right);
	printf("%d " , header->number);
}

int main(void)
{
    int i ; 
    int buffer[10] ;
    TREE *header = NULL ;
    for(i = 0 ; i < 10 ; i++)
    {
        buffer[i] = rand()%100 ;
    }
    for(i = 0 ; i < 10 ; i++)
    {
        //给树插入元素 
        insert_tree(&header , buffer[i]);
    }
    print_tree(header , 1);
    printf("\n前序遍历\n");
    front(header);
    printf("\n中序遍历\n");
    middle(header);
    printf("\n后序遍历\n");
    back(header);
    getchar();
}