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();
}