rectify the code of binary search tree search function in c++

#include<iostream.h>
#include<conio.h>
#include<process.h>

struct tree_node
{
	tree_node *left;
	tree_node *right;
	int data;
} ;
class bst
{
	tree_node *root;
	public:
	bst()
	{
		root=NULL;
	}
	int isempty() 
	{
		return(root==NULL);
	}
	void insert(int item);
	bool search(tree_node * ,int); // 2 errors on this line
                                       // 1. Type name expected.
                                       // 2. Declaration missing ;   
};
bool search(tree_node* root,int data) { //error on this line(decl. syntax error)
	if(root == NULL) {
		return false;
	}
	else if(root->data == data) {
		return true;
	}
	else if(data <= root->data) {
		return Search(root->left,data);
	}
	else {
		return Search(root->right,data);
	}
}
void main()
{
	int digit;
	bst b;
        int number;
	cout<<"Enter number be searched\n";
	cin>>number;
	//If number is found, print "FOUND"
	if (b.search(root,number) == true) cout<<"Found\n";
	else cout<<"Not Found\n";
	getch();
}