搜索——二叉搜索树

//二t叉?搜?索??树???的??搜?索??
#include <stdio.h>
#include <stdlib.h>
typedef int KeyType;
typedef struct node{
                KeyType key;
                 struct node *lchild,*rchild;
}BSTNode;

int Compare(int index1,int index2)
{
                 if(index1>index2)
                                 return 1;
                 if(index1<index2)
                                 return -1;
                 return 0;
}
BSTNode * bst_search(BSTNode* t,KeyType k)
{
                 if(t==NULL)
                                 return NULL;
                 else
                {
                                 switch(Compare(k,t->key))
                                {
                                 case 0:
                                                 return (t);
                                 case 1:
                                                 return (bst_search(t->rchild,k));
                                 case -1:
                                                 return (bst_search(t->lchild,k));
                                }
                }
}
 
void main()
{
                BSTNode * ptrtemp = NULL;
                ptrtemp = (BSTNode*)malloc( sizeof(BSTNode));
                ptrtemp->key = 30;
                
                BSTNode* l1,*r1,*l2;
                l1=(BSTNode*)malloc( sizeof(BSTNode));
                r1=(BSTNode*)malloc( sizeof(BSTNode));
                l2=(BSTNode*)malloc( sizeof(BSTNode));
                ptrtemp->lchild = l1;
                ptrtemp->rchild = r1;
                l1->lchild = l2;
                l1->key = 5;
                l1->rchild = NULL;
                r1->key = 40;
                r1->lchild = NULL;
                r1->rchild = NULL;
                l2->key = 2;
                l2->lchild =NULL;
                l2->rchild = NULL;
                BSTNode* result;
                KeyType searched =2;
                result = bst_search(ptrtemp,searched);
                 if(result!=NULL)
                printf( "%d",result->key);
}