Determine if two binary trees are equal

Question

What would be the efficient algorithm to find if two given binary trees are equal - in structure and content?

Answer 1

bool identical(node* root1,node* root2){
    if(root1 == NULL && root2 == NULL)
        return true;
    if(root1==NULL && root2!=NULL || root1!=NULL && root2 == NULL)
        return false;
    if(root1->data == root2->data){
        bool lIdetical = identical(root1->left,root2->left);
        if(!lIdentical)
            return false;
        bool rIdentical = identical(root1->right,root2->identical);
        return lIdentical && rIdentical;
    }
    else{
        printf("data1:%d vs data2:%d",root1->data,root2->data);
        return false;
    }
}

I do not know if this is the most effecient but I think this works.