Adding parent name to boost ptree

Question

I have a boost ptree with nodes:

pt.put("a.b", 1.0);
pt.put("a.c", 2.0);
pt.put("b.g", 3.0);

I would like the extract a tree that has "a.b" and "a.c" (but not "b.g"). When I use pt.get_child("a") I get a tree with "b" and "c". Is there a way to do this?

Answer 1

What you describe already works. See it Live On Coliru

If you want to filter out anything "non-a", just

• delete the other nodes Live on Coliru

  for (auto it = pt.begin(); it != pt.end();)
  {
      if (it->first != "a")
          it = pt.erase(it);
      else
          ++it;
  }
  

• create a new tree Live on Coliru

  ptree pt2;
  pt2.add_child("a", pt.get_child("a"));