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Here we will see some different types of variable declaration based on integer pointers integer constants and the integer constant pointers.To determine them we will use the Clockwise/Spiral Rule. By discussing the terms, we can understand the rules also.The const int *. This is used to tell the compiler that this is a pointer type variable, and this can store address of some constant int. The Clock rule is saying like this −Now the another one is const int * const. This is used to denote that this is one constant pointer variable, which can store the address of another ... Read More
To query for multiple parameters in MongoDB, you can use the dot(.) notation. Let us first create a collection with documents −> db.multipleParametersDemo.insertOne( ... { ... "CustomerName" : "Larry", ... "CustomerDetails" : [ ... { ... "CustomerCountryName" : "US", ... "CustomerBankName" : "HDFC", ... "CustomerBalance" : 17363, ... } ... ], ... "Purchase" : 1456, ... ... } ... ); ... Read More
To set the background color of a single tab, use the setBackgroundAt() method. This gives an option to mention the index and the color. The index here is the index of the specific tab you want to color.Let us first create a JTabbedPane −JTabbedPane tabbedPane = new JTabbedPane();Now, set the background color for one of the tabs with index 2 −tabbedPane.setBackgroundAt(2, Color.RED);The following is an example to set the background color of a single tab in a JTabbedPane container −Examplepackage my; import javax.swing.*; import java.awt.*; public class SwingDemo { public static void main(String args[]) { JFrame ... Read More
You can use the field() for this. Let us first create a table −mysql> create table DemoTable ( Value int ); Query OK, 0 rows affected (0.80 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(70); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(60); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(56); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(81); Query OK, 1 row affected (0.44 sec) mysql> ... Read More
PointersPointer variables are used to store the address of variable.SyntaxType *pointer;InitializationType *pointer; Pointer=variable name;ReferencesWhen a parameter is declared as reference, it becomes an alternative name for an existing parameter.SyntaxType &newname=existing name;InitializationType &pointer; Pointer=variable name;The main differences between pointers and reference parameters are −References are used to refer an existing variable in another name whereas pointers are used to store address of variable.References cannot have a null value assigned but pointer can.A reference variable can be referenced by pass by value whereas a pointer can be referenced by pass by reference.A reference must be initialized on declaration while it is not ... Read More
Here we will see how we can shut down the system by writing a simple C or C++ code. The shutdown process varies in different OS. If we are Linux user, we can use this terminal command to shut down.shutdown –P nowIf we are using Windows system, we can use this command −c:\windows\system32\shutdown /iWe will see the code for Linux and WindowsExample(Linux)#include using namespace std; int main() { system("shutdown -P now"); }Example(Windows)#include using namespace std; int main() { system("c:\windows\system32\shutdown /i "); }
The extern “C” keyword is used to make a function name in C++ have the C linkage. In this case the compiler does not mangle the function. Let us see what is the mangling in C++ first, then we can discuss about the extern “C” keyword.In C++ we can use the function overloading feature. Using this feature, we can create functions with same name. The only difference is the type of the arguments, and the number of arguments. The return type is not considered here. Now the question comes how the C++ distinguishes overloaded functions in object code?In the object ... Read More
You can use remove() for this. Let us first create a collection with documents −> db.deleteDataDemo.insertOne({_id:1, "Name":"Larry"}); { "acknowledged" : true, "insertedId" : 1 } > db.deleteDataDemo.insertOne({_id:2, "Name":"Chris"}); { "acknowledged" : true, "insertedId" : 2 } > db.deleteDataDemo.insertOne({_id:3, "Name":"Robert"}); { "acknowledged" : true, "insertedId" : 3 } > db.deleteDataDemo.insertOne({_id:4, "Name":"David"}); { "acknowledged" : true, "insertedId" : 4 } > db.deleteDataDemo.insertOne({_id:5, "Name":"Carol"}); { "acknowledged" : true, "insertedId" : 5 } > db.deleteDataDemo.insertOne({_id:6, "Name":"Sam"}); { "acknowledged" : true, "insertedId" : 6 }Following is the query to display all documents from a collection with the help of find() method −> db.deleteDataDemo.find().pretty();This will produce ... Read More
To add empty border, use the createEmtyBorder() method. Let us first create a new JLabel −JLabel label; label = new JLabel("Label with empty border!");Now, set empty border using the setBorder() method −label.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));The following is an example to add empty border to JPanel −Examplepackage my; import javax.swing.BorderFactory; import java.awt.Font; import javax.swing.JFrame; import javax.swing.JLabel; public class SwingDemo { public static void main(String[] args) throws Exception { JFrame frame = new JFrame("Demo"); JLabel label; label = new JLabel("Label with empty border!"); label.setFont(new Font("Verdana", Font.PLAIN, 16)); ... Read More
To set multidimensional array into a table, we need the values for rows and columns. Therefore, create a multidimensional array for rows −Integer[][] marks = { { 70, 66, 76, 89, 67, 98 }, { 67, 89, 64, 78, 59, 78 }, { 68, 87, 71, 65, 87, 86 }, { 80, 56, 89, 98, 59, 56 }, { 75, 95, 90, 73, 57, 79 }, { 69, 49, 56, 78, 76, 77 } };Now, columns −String students[] = { "S1", "S2", "S3", "S4", "S5", "S6"};Add the rows and columns set above to the ... Read More