Symmetric Tree

Given a binary tree, check whether it is a mirror of itself.
For example, the binary tree[1,2,2,3,4,4,3] is a symmetric tree.

Notes
bonus points if you could solve it both recursively and iteratively.

/*
struct TreeNode{
    int val;
    TreeNode *left;
    TreeNode *right;

*/

class solution{
    public:
        bool isSymmetric(TreeNode *root)(
            if(!root)
                return true;
            else
                return compareChild(root->left, root->right)
    private:
        bool compareChild(TreeNode *rroot, TreeNode *lroot){
            if(!lroot)
                return rroot == NULL;
            if(rroot == NULL)
                return false;
            if(lroot->val != rroot->val)
                return false;
            return compareChild(rroot->left, lroot->right) &&  compareChild(rroot->right, lroot->left);
        }
}