Check if a tree is a subtree of another tree

C++ program to check if the tree is a sub tree of another tree:
bool matchTree(Tree *r1, Tree *r2)
{
/* Nothing left in the subtree */
if(r1 == NULL && r2 == NULL)
return true;
/* Big tree empty and subtree not found */
if(r1 == NULL || r2 == NULL)
return false;
/* Not matching */
if(r1->data != r2->data)
return false;
return (matchTree(r1->left, r2->left) &&
matchTree(r1->right, r2->right));
}

bool subTree(Tree *r1, Tree *r2)
{
/*Big tree empty and subtree not found */
if(r1 == NULL)
return false;
if(r1->data == r2->data)
if(matchTree(r1, r2)) return true;
return (subTree(r1->left, r2) || subTree(r1->right, r2));
}

bool isSubTree(Tree *r1, Tree *r2)
{
/* Empty tree is subtree */
if(r2 == NULL)
return true;
else
return subTree(r1, r2);
}


For other tree operations or complete code refer to : click here