Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
MS-DOS is an operating system created for personal computers. It was developed by Microsoft. It is a classic example of an operating system with a layered structure. MS-DOS operating system is split into various layers and each of the layers have different functionalities.Layering provides a distinct advantage in the MS-DOS operating system because all the layers can be defined separately and interact with each other as required. Also, it is easier to create, maintain and update the system if it is done in the form of layers. Change in one layer specification does not affect the rest of the layers. ... Read More
Memory management plays an important part in the operating system. It deals with memory and the moving of processes from disk to primary memory for execution and back again.Some activities of an operating system with regards to memory management are −Memory AllocationA simple way to allocate memory is to provide the empty memory spaces to incoming processes as required. This can be done using the following algorithms −First-FitThe first available memory space that is large enough for the process purposes is allocated. Searching can start at the beginning or at the point where the last first-fit search ended.Best-FitThe smallest memory ... Read More
Environment.Exit() methodThe Environment.Exit() method terminates the process and returns an exit code to the operating system −Environment.Exit(exitCode);Use exitCode as 0 (zero) to show that the process completed successfully.Use exitCode as a non-zero number to show an error, for example −Environment.Exit(1) − Return a value 1 to show that the file you want is not presentEnvironment.Exit(2) − Return a value 2 to indicate that the file is in an incorrect format.System.Windows.Forms.Application.ExitThread( )To close a subapplication or current thread in a Windows Form, use theSystem.Windows.Forms.Application.ExitThread( ).private void buttonClose_Click(object sender, EventArgs eventArgs) { System.Windows.Forms.Application.ExitThread( ); }Read More
Commonly used wildcard characters are the asterisk (*). It represents zero or more characters in a string of characters.In the following example asterisk is used to match words that begins with m and ends with e −@”\bt\S*s\b”The following is the complete code −Example Live Demousing System; using System.Text.RegularExpressions; namespace Demo { public class Program { private static void showMatch(string text, string expr) { MatchCollection mc = Regex.Matches(text, expr); foreach (Match m in mc) { Console.WriteLine(m); } ... Read More
Unmanaged CodeApplications that are not under the control of the CLR are unmanagedThe unsafe code or the unmanaged code is a code block that uses a pointer variable.The unsafe modifier allows pointer usage in unmanaged code.Let us see the example −Examplestatic unsafe void Main(string[] args) { int var = 20; int* p = &var; Console.WriteLine("Data is: {0} ", var); Console.WriteLine("Address is: {0}", (int)p); Console.ReadKey(); }Managed CodeManaged code is a code whose execution is managed by Common Language Runtime. It gets the managed code and compiles it into machine code. After that, the code is executed.The ... Read More
To search files from the list of files in a directory, try to run the following code −Exampleusing System; using System.IO; namespace Demo { class Program { static void Main(string[] args) { //creating a DirectoryInfo object DirectoryInfo mydir = new DirectoryInfo(@"d:\amit"); // getting the files in the directory, their names and size FileInfo [] f = mydir.GetFiles(); foreach (FileInfo file in f) { Console.WriteLine("File Name: {0} Size: ... Read More
Firstly, set an array with values −int[] myArr = new int[] { 34, 23, 77, 67 };To get the average, firstly get the sum of array elements.Divide the sum with the length of the array and that will give you the average of the elements −int sum = 0; int average = 0; for (int i = 0; i < len; i++) { sum += myArr[i]; } average = sum / len;The following is the complete code to get the array in C# −Example Live Demousing System; public class Program { public static void Main() ... Read More
DynamicStore any type of value in the dynamic data type variable created using dynamic keyword. Type checking for these types of variables takes place at run-time. Dynamic are dynamically typed variables.The following is the syntax for declaring a dynamic type −dynamic = value;The following is an example −dynamic val1 = 100; dynamic val2 = 5; dynamic val3 = 20;The dynamic types are similar to object types except that type checking for object type variables takes place at compile time, whereas that for the dynamic type variables takes place at runtime.VarThe "var" keyword initializes variables with var support. Just assign ... Read More
Abstract methods do not provide an implementation and they force the derived classes to override the method. It is declared under abstract class. An abstract method only has the method definitionVirtual methods have an implementation, unlike the Abstract method and it can exist in the abstract and non-abstract class. It provides the derived classes with the option of overriding it.Virtual FunctionsThe virtual keyword is useful in modifying a method, property, indexer, or event. When you have a function defined in a class that you want to be implemented in an inherited class(es), you use virtual functions. The virtual functions could ... Read More
As we know that we can see the list of tables in a database with the help of SHOW TABLES statement. But MySQL temporary tables are not stored in this list or in other words we can say that we cannot see the temporary tables with the help of SHOW TABLES statement. To illustrate it we are using the following example −ExampleIn this example, we are trying to get the temporary table named ‘SalesSummary’ from SHOW TABLES statement as follows −mysql> SHOW TABLES LIKE '%Sales%'; Empty set (0.00 sec) mysql> SHOW TABLES LIKE '%SalesSummary%'; Empty set (0.00 sec)The above ... Read More