Find binary tree height

Question

I am trying to write a function to get the height of a binary tree. When I print the value of the maxi the value is what I expect but when the function returns the value, the value is always 0. Can someone tell what I am doing wrong here?

int treeHeight(tree *p)
{
    static int maxi=0;
    static int i=0;
    if(p==NULL)
    {
        return maxi;
    }
    else
    {
        if(p->left!=NULL||p->right!=NULL)
        {
            i++;
        }
        else
        {
            i++;
            if(maxi<i)
            {
                maxi=i;
            }
        }
        treeHeight(p->left);
        treeHeight(p->right);
        i--;
    }
}

Solution

Your treeHeight function should look like the following:

int treeHeight(tree *p)
{
   if (p == NULL)
   {
      return -1;
   }

   int left = treeHeight(p->left);
   int right = treeHeight(p->right); 

   return 1 + std::max(left, right);
}

Why do you need to static variables i and maxi there? You don't need those variables there to find out the height of a binary tree.