Is Binary Tree?

Given a binary tree,write an algorithm to find if the tree is a binary search tree or not.

Simple Recursive call is good..

int check_tree(bst *node)
{
if(!node)
return TRUE;
if(node->left!=NULL && node->infoleft))
return(false);
if(node->right!=NULL && node->inforight))
return(false);
if(!check_tree(node->left) || !check_tree(node->right))
return(false);
return(true);
}

I have already posted better algorithm in my tree sections earlier.
Set Min and Max to INT_MIN and INT_MAX
bool IsBst( node *root, int min, int max)
{
if (!root) return true;
if ( !isBst( root->left,min,root->info) return false;
if ( !isBst(root->right,root->info,max) return false;
return true;
}