c++ prog bst

#include<iostream>
#define SPACE 10
using namespace std;
class treenode
{
public:
	int value;//data
	treenode *left;
	treenode *right;
	treenode()
	{
		value=0;
		left=NULL;
		right=NULL;
	}
	treenode(int v)
	{
		value=v;
		left=NULL;
		right=NULL;
	}
};

class bst
{
public:
	treenode *root;
	bst()
	{
		root=NULL;
	}


	bool isempty()
	{
		if(root==NULL)
		{
			return true;	
		}
		else
		{
			return false;
		}
	}	
	void insertnode(treenode *newnode)
	{
		if(root==NULL)
		{
			root=newnode;
			cout<<"value inserted as root node"<<endl;	
		}
		else
		{
			treenode *temp=root;
			while(temp!=NULL)
			{

				if(newnode->value==temp->value)
				{
					cout<<"value alreasy exists , insert another"<<endl;
					return;
				}
				else if((newnode->value<temp->value)&&(temp->left==NULL))
				{
					temp->left=newnode;
					cout<<"value inserted in left";
					break;
				}	
				else if(newnode->value<temp->value)
				{
					temp=temp->left;
				}	
				else if((newnode->value>temp->value)&&(temp->right==NULL))
				{
					temp->right=newnode;
					cout<<"value inserted in right";
					break;
				}	
				else if(newnode->value>temp->value)
				{
					temp=temp->right;
				}	
			}
		}
	}

	void searchnode()
	{
		
	}

	void print2d(treenode *r,int space)
	{
		if(r==NULL)
			return;
		space +=SPACE;
		print2d(r->right,space);
		cout<<endl;
		for(int i=SPACE;i<space;i++)
			cout<<" ";
		cout<<r->value<<"\n";
		print2d(r->left,space);
	}

};
int main()
{
	int option,val;
	bst obj;
	do
	{	cout<<"\n";
		cout<<"SELECT THE OPTION NUMBER"<<endl;
		cout<<"1.INSERT NODE"<<endl;
		cout<<"2.SEARCH NODE"<<endl;
		cout<<"3.DELETE NODE"<<endl;
		cout<<"4.PRINT BST VALUES"<<endl;
		cout<<"0.EXIT"<<endl;
		cin>>option;
		treenode *newnode= new treenode();//we used heap memory
		switch(option)
		{
			case 0:
				break;
			case 1: cout<<"insert"<<endl;
					cout<<"enter the value to insert in bst";
					cin>>val;
					newnode->value=val;
					obj.insertnode(newnode);
					cout<<endl;
					break;
			case 2: cout<<"search"<<endl;
					break;
			case 3: cout<<"delete"<<endl;
					break;
			case 4: cout<<"print value"<<endl;
					obj.print2d(obj.root,5);
					break;						
			default:cout<<"enter correct option"<<endl;	
		}

	}
	while(option!=0);

	return 0;
}