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To generate ObjectID, use the below syntax in the MonogDB shell −new ObjectId()Let us implement the above syntax to generate ObjectID in MongoDB −> new ObjectId() ObjectId("5cd7bf2f6d78f205348bc646") > new ObjectId() ObjectId("5cd7bf316d78f205348bc647") > new ObjectId() ObjectId("5cd7bf336d78f205348bc648") > new ObjectId() ObjectId("5cd7bf346d78f205348bc649") > new ObjectId() ObjectId("5cd7bf356d78f205348bc64a") > new ObjectId() ObjectId("5cd7bf396d78f205348bc64b") > new ObjectId() ObjectId("5cd7bf3a6d78f205348bc64c")As shown above, every time you will get a new ObjectId.
Yes, We can create a generator by using iterators in python Creating iterators is easy, we can create a generator by using the keyword yield statement. Python generators are an easy and simple way of creating iterators. and is mainly used to declare a function that behaves like an iterator.The generator is a function which we can iterate over one value at a time most probably in a day to day life, every programmer will use iterable objects like lists, strings, and Dict, etc. An iterator is an object that can be iterated through looping.The following example shows that Generators introduce Yield ... Read More
Keywords − Keywords in Java convey a special meaning to the compiler therefore, these cannot be used as identifiers. Java provides a set of 50 keywords.abstractcontinuefornewswitchassertdefaultgotopackagesynchronizedbooleandoifprivatethisbreakdoubleimplementsprotectedthrowbyteelseimportpublicthrowscaseenuminstanceofreturntransientcatchextendsintshorttrycharfinalinterfacestaticvoidclassfinallylongstrictfpvolatileconstfloatnativesuperwhileReserved words − Among the list of key words list mentioned above the key words goto and const are currently not in use. They are reserved words (for the future use).The true false and null − True, false and null represents certain values in Java, they are used as literals. They are not considered as keywords.Still, you cannot use them as identifiers in Java if you try to do so, a compile time error will ... Read More
The HTML DOM select Object represent the element of an HTML document.Let’s see how to create select objectSyntaxFollowing is the syntax −document.createElement(“SELECT”);PropertiesFollowing are the properties of select Object −PropertyExplanationautofocusIt returns and modify whether the drop-down list should get focused or not when page load.disabledIt returns and modify whether the drop-down list is disabled or not.lengthIt returns the number of elements inside a drop-down list in an HTML document.formIt returns the reference of the form that contain the drop-down list in the HTML document.multipleIt returns and modify whether multiple options can be selected from a drop-down list or not.nameIt returns ... Read More
Here we will see how to count number of matchsticks are required to make the pyramid-like below. The base of the pyramid is given. So if the base is 1, it will take 3 matchsticks to make a pyramid, for base 2, 9 matchsticks are needed, for base size 3, it will take 18 matchsticks.To solve this problem, we have to use this formula −Example Live Demo#include using namespace std; int main(){ int x; cout > x; int count = 3*x*(x+1)/2; cout
C++ boost libraries are widely useful library. This is used for different sections. It has large domain of applications. For example, using boost, we can use large number like 264 in C++.Here we will see some examples of boost library. We can use big integer datatype. We can use different datatypes like int128_t, int256_t, int1024_t etc. By using this we can get precision up to 1024 easily.At first we are multiplying two huge number using boost library.Example#include #include using namespace boost::multiprecision; using namespace std; int128_t large_product(long long n1, long long n2) { int128_t ans = (int128_t) n1 * ... Read More
In C the strings are basically array of characters. In C++ the std::string is an advancement of that array. There are some additional features with the traditional character array. The null terminated strings are basically a sequence of characters, and the last element is one null character (denoted by ‘\0’). When we write some string using double quotes (“…”), then it is converted into null terminated strings by the compiler.The size of the string may smaller than the array size, but if there are some null character inside that array, that will be treated as the end of that string.See ... Read More
One of the variant of the getConnection() method of the DriverManager class accepts url of the database, (String format) a properties file and establishes connection with the database.Connection con = DriverManager.getConnection(url, properties);To establish a connection with a database using this method −Set the Driver class name as a system property −System.setProperty("Jdbc.drivers", "com.mysql.jdbc.Driver");Create a properties object as −Properties properties = new Properties();Add the user name and password to the above created Properties object as −properties.put("user", "root"); properties.put("password", "password");Finally invoke the getConnection() method of the DriverManager class by passing the URL and, properties object as parameters.//Getting the connection String url = "jdbc:mysql://localhost/mydatabase"; Connection con = ... Read More
To query null value in MongoDB, use $ne operator. Let us first create a collection with documents −> db.queryingNullDemo.insertOne( ... { ... "StudentName":"Larry", ... "StudentDetails": ... { ... "StudentAge":21, ... "StudentSubject":"MongoDB" ... } ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5cd00bec588d4a6447b2e05f") } > db.queryingNullDemo.insertOne( ... { ... "StudentName":"Sam", ... "StudentDetails": ... { ... "StudentAge":23, ... ... Read More
To enable row selection, use the setRowSelectionAllowed () method and set it to TRUE −table.setCell setRowSelectionAllowed(true);The following is an example to enable row selection in a JTable −Examplepackage my; import java.awt.Color; import javax.swing.BorderFactory; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.border.TitledBorder; public class SwingDemo { public static void main(String[] args) { JFrame frame = new JFrame(); JPanel panel = new JPanel(); panel.setBorder(BorderFactory.createTitledBorder( BorderFactory.createEtchedBorder(), "ODI Rankings", TitledBorder.CENTER, TitledBorder.TOP)); String[][] rec = { { "1", "Steve", "AUS" }, ... Read More