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Articles by George John
Page 51 of 79
Listing modified, old and newly created files on Linux using C++
Here we will see how to list the modified files and old and newly created files on Linux platform using C++ program.The task is very simple. We can use the Linux shell command to get the files in desired order. The ls –l command is used to get all of the files in long listing format. Here we will add more options to sort them based on time. (Ascending and Descending). The –t command is used to sort based on time, and –r can be added to reverse the sequence.The command will be like below:ls –lt ls –ltrWe will use ...
Read MoreHow to perform SELECT using COUNT in MySQL?
To perform SELECT with COUNT, use aggregate function COUNT(). Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(100), Subject varchar(100) ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Name, Subject) values('John', 'MySQL'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Name, Subject) values('John', 'Java'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Name, Subject) values('Carol', 'MongoDB'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(Name, Subject) values('Carol', ...
Read MoreWhat are all the common undefined behaviours that a C++ programmer should know about?
In C++, there are some undefined behaviors. These are identified by doing some tasks in C++. There are no such direct definitions. These few things should be known to all of the programmers, who want to use C++ for different purposes.Here we will see some C++ Codes. and try to guess the results. The codes will generate some runtime errors.The Divide By Zero error is undefined.Example Code#include using namespace std; int main() { int x = 10, y = 0; int z = x / y; cout
Read MoreHidden features of C++
Here we will see some good features and tricks of C++ programming language that can help us in different area. Like if we want to participate in some competitive programming events, then these tricks will help us to reduce the time for writing codes. Let us see some of these examples one by one.Checking whether a number is odd or even without using % operator. This trick is simple. We can perform bitwise AND operation with the number and 1. If the result is non-zero then this is odd, otherwise this is even. The logic is too simple. All odd ...
Read MoreHow to get the date between TODAY and TODAY-7"?
To get the date between dates, you need to use. Here, we are getting the dates between today and today-7 days −select *from yourTableName where DATE(yourColumnName) > (NOW() - INTERVAL 7 DAY);Note : Let’s say the current date is '2019-06-02’ Let us first create a table.mysql> create table DemoTable ( LoginDate date ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2018-03-21'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('2019-05-22'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('2019-05-27'); ...
Read MoreIs name a reserved word in MySQL?
No, name is not a reserved word in MySQL, you can use without backtick symbol. If you are working on a reserved word then use backtick symbol. Let us first create a table −mysql> create table name ( name varchar(10) ); Query OK, 0 rows affected (0.78 sec)Now you can insert some records in the table using insert command −mysql> insert into name values('John'); Query OK, 1 row affected (0.13 sec) mysql> insert into name values('Carol'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from name;Output+-------+ | name ...
Read MoreI/O Redirection in C++
In C, we can use the freopen() function for redirection purposes. Using this function, we can redirect existing FILE pointer to another stream. The syntax of the freopen is like below:FILE *freopen(const char* filename, const char* mode, FILE *stream)In C++ also, we can do the redirection. In C++, the streams are used. Here we can use our own stream, and also redirect system streams. In C++, there are three types of streams.istream : Stream, that can support input onlyostream : Stream, that can support output onlyiostream : These can be used for input and output.These classes, and file stream classes ...
Read MoreJava Program to set different height for multiple rows in JTable
To set different height for multiple rows, use the setRowHeight() method for separate rows for which you want to increase the row height. Let us first see an example to create a table with same height for all the rows −Examplepackage my; import java.awt.Color; import java.awt.Font; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; public class SwingDemo { public static void main(String[] argv) throws Exception { DefaultTableModel tableModel = new DefaultTableModel(); JTable table = new JTable(tableModel); tableModel.addColumn("Language/ Technology"); tableModel.addColumn("Text Tutorial"); tableModel.addColumn("Video Tutorial"); ...
Read MoreMySQL automatic conversion on lowercase? Is this possible?
Yes, it is possible with triggers. You can create trigger for automatic conversion on lower case. Let us first create a table −mysql> create table DemoTable ( StudentSubject text ); Query OK, 0 rows affected (0.61 sec)Let us create a trigger for automatic conversion on lower case −mysql> CREATE TRIGGER lowerCaseOnInsertDemo BEFORE INSERT ON DemoTable FOR EACH ROW SET NEW.StudentSubject = LOWER(NEW.StudentSubject); Query OK, 0 rows affected (0.21 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('MOngoDb'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('JaVA'); Query OK, ...
Read MoreHow to disable close button on a JFrame in Java?
To disable the close button, let us first create a frame −JFrame frame = new JFrame("Login!");Use the setDefaultCloseOperation() to set the status of the close button. Set it to DO_NOTHING_ON_CLOSE to disable it −frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);The following is an example to disable close button on a JFrame in Java −Examplepackage my; import java.awt.GridLayout; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPasswordField; import javax.swing.JTextField; import javax.swing.SwingConstants; public class SwingDemo { public static void main(String[] args) throws Exception { JFrame frame = new JFrame("Login!"); JLabel label1, label2, label3; frame.setLayout(new GridLayout(2, 2)); label1 = ...
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