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The Copy constructor and the assignment operators are used to initializing one object to another object. The main difference between them is that the copy constructor creates a separate memory block for the new object. But the assignment operator does not make new memory space. It uses the reference variable to point to the previous memory block.Copy Constructor (Syntax)classname (const classname &obj) { // body of constructor }Assignment Operator (Syntax)classname Ob1, Ob2; Ob2 = Ob1;Let us see the detailed differences between Copy constructor and Assignment Operator.Copy ConstructorAssignment OperatorThe Copy constructor is basically an overloaded constructorAssignment operator is ... Read More
You cannot update it but you can save a new id and remove the old id. Follow some steps in order to update the _id of a MongoDB. The steps are as follows:Step1: In the first step, you need to store ObjectId into a variable.anyVariableName=db.yourCollectionName.findOne({_id:yourObjectIdValue)});Step 2: In the second step, you need to set a new id.yourDeclaredVariableName._id=yourNewObjectIdValue;Step 3: In the third step, you need to insert new id on a document.db.yourCollectionName.insert(yourDeclaredVariableName);Step 4: In the fourth step, you need to remove the old id.db.yourCollectionName.remove({_id:yourOldObjectIdValue)});To understand the above steps, let us create a collection with document. The query to create a collection ... Read More
Following are the few options to maintain the session between the Web Client and the Web Server −CookiesA webserver can assign a unique session ID as a cookie to each web client and for subsequent requests from the client they can be recognized using the received cookie.This may not be an effective way as the browser at times does not support a cookie. It is not recommended to use this procedure to maintain the sessions.Hidden Form FieldsA web server can send a hidden HTML form field along with a unique session ID as follows −This entry means that, when the ... Read More
To set a new value in the Decade Tuple, you need to use the setAtX() method. Here, X is the index wherein you want to set the value. For example, setAt2() sets the value at index 2. The value to be included is to be set as the value in the parameter, likesetAt2(“Amit”);Let us first see what we need to work with JavaTuples. To work with Decade class in JavaTuples, you need to import the following packageimport org.javatuples.Decade;Note Download JavaTuples Jar library to run JavaTuples program. If you are using Eclipse IDE, then Right Click Project -> Properties -> Java ... Read More
Folium is a very powerful python library which let you create seveal kind of Leaflet maps. As Leaflet/folium maps are interactive, so they are ideal for making dashborad building.InstallationInstalling folium is very easy using pip −$pip install foliumLike you can see from the below screenshot, you just need to type above command in your console/cmd and pip will install the folium as well as dependencies for your python installation.Basic Map#Import library import folium #Uses lat then lon. & zoomlevel 4.The bigger the zoom number, the closer in you get. mapOBJ = folium.Map(location=[17.3616, 78.4747], zoom_start = 4, tiles = 'Stamen ... Read More
An immutable copy of a LocalDateTime object where some weeks are added to it can be obtained using the plusWeeks() method in the LocalDateTime class in Java. This method requires a single parameter i.e. the number of weeks to be added and it returns the LocalDateTime object with the added weeks.A program that demonstrates this is given as follows −Example Live Demoimport java.time.*; public class Demo { public static void main(String[] args) { LocalDateTime ldt = LocalDateTime.now(); System.out.println("The current LocalDateTime is: " + ldt); System.out.println("The LocalDateTime with 4 weeks added is: ... Read More
You can use row_count() at the end for this. Let us first create a table −mysql> create table rowAfftectedByDeleteDemo -> ( -> CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CustomerName varchar(20) -> ); Query OK, 0 rows affected (0.86 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('John'); Query OK, 1 row affected (0.14 sec) mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Carol'); Query OK, 1 row affected (0.10 sec) mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Bob'); Query OK, 1 row affected (0.09 sec) mysql> insert into rowAfftectedByDeleteDemo(CustomerName) values('Sam'); Query ... Read More
You can create a table same as an existing table using the following syntax:CREATE TABLE new_table as SELECT * from old_table;Assume we have a table named dispatches with 5 records as shown below:+-------------+--------------+--------------+--------------+-------+----------------+ | ProductName | CustomerName | DispatchDate | DeliveryTime | Price | Location | +-------------+--------------+--------------+--------------+-------+----------------+ | Key-Board | Raja | 2019-09-01 | 05:30:00 | 7000 | Hyderabad | | Earphones | Roja | 2019-05-01 | 05:30:00 | 2000 | Vishakhapatnam | | Mouse ... Read More
Before getting into example, we should know test scenario. In login page, usually we takes email id and pass word from edit text. While taking email id from editext. we should know, it is valid format or not.This example demonstrate about how to check edit text's text is email address or not.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above layout we have added edit text and ... Read More
To get connected clients in MongoDB, use currentOp() with the set value to true and you need to iterate array result set with the help of field client. Let us first implement currentOp> db.currentOp(true)Following is the output. Here the client is 127.0.0.1 since we are using localhost. The output displays all the connected clients{ "inprog" : [ { "host" : "DESKTOP-QN2RB3H:27017", "desc" : "conn1", "connectionId" : 1, "client" : "127.0.0.1:61787", "appName" : "MongoDB Shell", ... Read More