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In C++ we can overload some operators like +, -, [], -> etc. But we cannot overload any operators in it. Some of the operators cannot be overloaded. These operators are like below? “.” Member access or dot operator? “? : ” Ternary or conditional operator? “::” Scope resolution operator? “.*” Pointer to member operator? “sizeof” The object size operator? “typeid” Object type operatorThese operators cannot be overloaded because if we overload them it will make serious programming issues.For an example the sizeof operator returns the size of the object or datatype as an operand. This is evaluated by the ... Read More
To remove array element by its index in MongoDB, you can use $unset and $pull operator. There are two steps to remove array elements from an array.The syntax for the same is as follows:db.yourCollectionName.update({}, {$unset:{"yourArrayListName.yourPosition":yourPositionValue}}; db.yourCollectionName.update({}, {$pull:{"yourArrayListName":null}});To understand the above syntax, let us create a collection with document. The query to create a collection with document is as follows:>db.removeArrayElements.insertOne({"StudentName":"Larry", "StudentAge":23, "TechnicalSub ject":["C", "C++", "Java", "MongoDB"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c6ea4879c4643706aef56d2") }Display all documents from a collection with the help of find() method. The query is as follows:> db.removeArrayElements.find().pretty();The following is the output:{ "_id" : ObjectId("5c6ea4879c4643706aef56d2"), ... Read More
Here is a summary of important methods available through the session object −Sr.No.Method & Description1public Object getAttribute(String name)This method returns the object bound with the specified name in this session, or null if no object is bound under the name.2public Enumeration getAttributeNames()This method returns an Enumeration of String objects containing the names of all the objects bound to this session.3public long getCreationTime()This method returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.4public String getId()This method returns a string containing the unique identifier assigned to this session.5public long getLastAccessedTime()This method returns the last ... Read More
Before getting into an example, we should know what SQLite database in android is. SQLite is an open source SQL database that stores data to a text file on a device. Android comes in with built in SQLite database implementation. SQLite supports all the relational database features. In order to access this database, you don't need to establish any kind of connections for it like JDBC, ODBC etc.This example demonstrates How to get the beginning of the first day of this week from the timestamp in Android SQLite.Step 1 − Create a new project in Android Studio, go to File ... Read More
Use the contains() method to search for a value in the KeyValue tuple. Let us first see what we need to work with JavaTuples. To work with KeyValue class in JavaTuples, you need to import the following package.import org.javatuples.KeyValue;Note Download JavaTuples Jar library to run JavaTuples program. If you are using Eclipse IDE, then Right Click Project -> Properties -> Java Build Path -> Add External Jars and upload the downloaded JavaTuples jar file. Refer the below guide for all the steps to run JavaTuples.Steps: How to run JavaTuples program in EclipseThe following is an example to implement the contains() ... Read More
The equality of two LocalDateTime objects can be determined using the equals() method in the LocalDateTime class in Java. This method requires a single parameter i.e. the LocalDateTime object to be compared. Also it returns true if both the LocalDateTime objects are equal and false otherwise.A program that demonstrates this is given as follows −Example Live Demoimport java.time.*; public class Main { public static void main(String[] args) { LocalDateTime ldt1 = LocalDateTime.parse("2019-02-18T23:15:30"); LocalDateTime ldt2 = LocalDateTime.parse("2019-02-18T23:15:30"); System.out.println("The LocalDateTime ldt1 is: " + ldt1); System.out.println("The LocalDateTime ldt2 is: " ... Read More
Let us first create a demo tablemysql> create table RandomNumberDemo -> ( -> MyNumber int -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into RandomNumberDemo values(17); Query OK, 1 row affected (0.20 sec) mysql> insert into RandomNumberDemo values(18); Query OK, 1 row affected (0.12 sec) mysql> insert into RandomNumberDemo values(29); Query OK, 1 row affected (0.49 sec)Display all records from the table using select statement. The query is as follows −mysql> select *from RandomNumberDemo;The following is the output+----------+ | MyNumber | ... Read More
The put() method of the ArrayBlockingQueue class inserts the specified element at the tail of this queue. It waits for the space to become available, if the queue is full.The syntax is as follows:void put(E e)Here, e is the element to be inserted.To work with ArrayBlockingQueue class, you need to import the following package:import java.util.concurrent.ArrayBlockingQueue;The following is an example to implement put() method of Java ArrayBlockingQueue class:Example Live Demoimport java.util.concurrent.ArrayBlockingQueue; public class Demo { public static void main(String[] args) throws InterruptedException { ArrayBlockingQueue q = new ArrayBlockingQueue(7); q.put(200); q.put(310); ... Read More
This might seem very useful for a lazy python programmer who keeps most of the files and folders at one location and sometimes at confused what all files are there and surely he is too lazy to do it manually. So below is a python program to organize or simplify everything in appropriate folder in the single go and remove empty directories.So we have a directory path where lots of files of different types are present (like below) and our program we segregate each file type into their respective folders (like below).Input folder structureDesired OutputFirst create different folders based on ... Read More
You can use $elemMatch operator for this. Let us create a collection with documents> db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-1", "Tag-2", "Tag-3"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c9eb4d5d628fa4220163b79") } > db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-2", "Tag-4", "Tag-5"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c9eb4d5d628fa4220163b7a") } > db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-6", "Tag-4", "Tag-3"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c9eb4d6d628fa4220163b7b") }Following is the query to display all documents from a collection with the help of find() method> db.getDocumentsByTagsDemo.find().pretty();This will produce the following output{ "_id" : ObjectId("5c9eb4d5d628fa4220163b79"), "Tags" : [ "Tag-1", "Tag-2", "Tag-3" ] } ... Read More