how to process logical operation between 2 BSONObj precreated in mongodb -

i'm new mongodb. want execute query (a=3 or b=5 condition) using c++ driver..

i can create separately 2 bsonobj objects each a=3 , b=5 through bsonobjbuilder follows.

 mongo::bsonobjbuilder builder = new mongo::bsonobjbuilder;  mongo::bsonobjbuilder inner = new bsonobjbuilder(builder->subobjstart(condition));  inner->append("$gte", value);  inner->append("$lte", value);   mongo::bsonobj obj = builder.obj(); 

so have 2 different bsonobj. , can run them successfully. how can combine these objects using $or or $and logical operators.

assuming goal query {$or: [{a: 3}, {a: 5}]}, construct mongodb c++ driver follows:

mongo::bsonobjbuilder querybuilder; mongo::bsonarraybuilder orclause(querybuilder.subarraystart("$or")); mongo::bsonobjbuilder firstclause(orclause.subobjstart()).append("a", 3).done(); mongo::bsonobjbuilder secondclause(orclause.subobjstart()).append("a", 5).done(); orclause.done(); mongo::bsonobj query(querybuilder.obj()); 

and here's less verbose way using or helper:

mongo::bsonobj query(or(bson("a" << 3), bson("a" << 5));