The concat() method in the Java IntStream class forms a concatenated stream. The elements of this stream are all the elements of the first stream followed by all the elements of the second stream.The syntax is as follows −static IntStream concat(IntStream one, IntStream two)Here, the parameter one is the first ... Read More

The functors are the function objects in C++. The functor allows an instance object of some class to be called as if it were an ordinary function. Let us consider a function that takes one argument. We can use this function as function object to do some task on a ... Read More

The equivalent syntax is as follows.db.yourCollectionName.find({}, {_id: 1, "column1": 1, "column2": 1}).pretty();To understand the above syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.equivalentForSelectColumn1Column2Demo.insertOne({"CustomerName":"John", "CustomerAge":26, "CustomerCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c92c6205259fcd19549980a") } ... Read More

The copy constructor is a constructor which creates an object by initializing it with an object of the same class, which has been created previously. The copy constructor is used to −Initialize one object from another of the same type.Copy an object to pass it as an argument to a ... Read More

To add elements to the AbstractCollection class, use the add() method. For example −absCollection.add("These"); absCollection.add("are"); absCollection.add("demo");To work with AbstractCollection class in Java, import the following package −import java.util.AbstractCollection;The following is an example to add elements to AbstractCollection class in Java −Example Live Demoimport java.util.ArrayList; import java.util.AbstractCollection; public class Demo { ... Read More

To list all collections in Mongo shell, you can use the function getCollectionNames().The syntax is as follows −db.getCollectionNames();You can use another command which is collections. The syntax is as follows −show collections;To list all collections in Mongo, use the above two functions. The query is as follows −> db.getCollectionNames();The following ... Read More

Set lower_bound() function in C++ STL returns an iterator pointing to the element in the container which is equivalent to k passed in the parameter. If k is not present in the set container, then the function returns an iterator pointing to the immediate next element which is just greater ... Read More

The containsAll() method checks for all the elements in the specified collection. It returns TRUE if this collection has all the elements. The methods check for each element one by one to see if it's contained in this collection.The syntax is as follows −public boolean containsAll(Collection c)To work with AbstractCollection ... Read More

Set::begin() function is a bidirectional iterator used to return an iterator pointing to the first element of the set container.Set::end() function is a bidirectional iterator used to return an iterator pointing to the last element of the set container.Example Code Live Demo#include #include using namespace std; int main() {   ... Read More

To return query based on the date in MongoDB, let us take an example.To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.returnQueryFromDate.insertOne({"PassengerName":"John", "PassengerAge":23, "PassengerArrivalTime":new ISODate("2018-03-10 14:45:56")}); {    "acknowledged" : true,    "insertedId" ... Read More