A static constructor is a constructor declared using a static modifier. It is the first block of code executed in a class. With that, a static constructor executes only once in the life cycle of class.The following is an example of static constructors in C# −Exampleusing System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Difference {    class Demo {       static int val1;       int val2;       static Demo() {          Console.WriteLine("This is Static Constructor");          val1 = 70;       }   ... Read More

The C# static class cannot be instantiated and can only have only static members. The static class in C# is sealed and cannot contain instance constructors.The following is an example with static class and static members −Exampleusing System; public static class Demo {    public static float PI = 3.14f;    public static int calc(int n){return n*n;} } class Program {    public static void Main(string[] args) {       Console.WriteLine("PI: "+Demo.PI);       Console.WriteLine("Square: " + Demo.calc(3));    } }Above, the static class is −public static class Demo {    public static float PI ... Read More

Sealed class in C# with the sealed keyword cannot be inherited. In the same way, the sealed keyword can be added to the method.When you use sealed modifiers in C# on a method, then the method loses its capabilities of overriding. The sealed method should be part of a derived class and the method must be an overridden method.Let us see an example of sealed class in C# −Exampleusing System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Demo {    class Program {       static void Main(string[] args) {          Result ob = new ... Read More

Recursive method call in C# is called Recursion. Let us see an example to calculate power of a number using recursion.Here, if the power is not equal to 0, then the function call occurs which is eventually recursion −if (p!=0) {    return (n * power(n, p - 1)); }Above, n is the number itself and the power reduces on every iteration as shown below −Exampleusing System; using System.IO; public class Demo {    public static void Main(string[] args) {       int n = 5;       int p = 2;       long res; ... Read More

Declare the reference parameters using the ref keyword. A reference parameter is a reference to a memory location of a variable. When you pass parameters by reference, unlike value parameters, a new storage location is not created for these parameters.Declare a ref parameter −public void swap(ref int x, ref int y) {}Declare a ref parameter of array type −static void Display(ref int[] myArr)The following is an example showing how to work with ref parameter of an array type in C# −class TestRef {    static void Display(ref int[] myArr) {       if (myArr == null) {     ... Read More

An exception is a problem that arises during the execution of a program. A C# exception is a response to an exceptional circumstance that arises while a program is running, such as an attempt to divide by zero.Define your own exception. User-defined exception classes are derived from the Exception class.The following is an example −Exampleusing System; namespace UserDefinedException {    class TestFitness {       static void Main(string[] args) {          Fitness f = new Fitness();          try {             f.showResult();          } catch(FitnessTestFailedException ... Read More

Copy Constructor creates an object by copying variables from another object.Let us see an example −Exampleusing System; namespace Demo {    class Student {       private string name;       private int rank;       public Student(Student s) {          name = s.name;          rank = s.rank;       }       public Student(string name, int rank) {          this.name = name;          this.rank = rank;       }       public string Display {     ... Read More

The System.Math class in C# provides methods are properties to perform mathematical operations, trigonometric, logarithmic calculations, etc.Some of its methods include −Sr.NoMethod & Description1Abs(Decimal)Returns the absolute value of a Decimal number.2Abs(Double)Returns the absolute value of a double-precision floating-point number.3Abs(Int16)Returns the absolute value of a 16-bit signed integer.4Abs(Int32)Returns the absolute value of a 32-bit signed integer.5Abs(Int64)Returns the absolute value of a 64-bit signed integer.6Abs(SByte)Returns the absolute value of an 8-bit signed integer.7Abs(Single)Returns the absolute value of a single-precision floating-point number.8Acos(Double)Returns the angle whose cosine is the specified number.9Asin(Double)Returns the angle whose sine is the specified number.10Atan(Double)Returns the angle whose tangent is ... Read More

The following are the logical operators that you can use on Strings in C#.OperatorDescriptionExample&&Called Logical AND operator. If both the operands are non zero then condition becomes true.(A && B) is false.||Called Logical OR Operator. If any of the two operands is non zero then condition becomes true.(A || B) is true.!Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.!(A && B) is true.Let us see an example showing how to use logical AND operator on strings −Example Live Demousing System; using System.Collections.Generic; using System.Linq; ... Read More

The Directory class in C# has many methods to perform operations on directories and sub-directories −Sr.NoMethod & Description1CreateDirectory(String)Creates all directories and subdirectories in the specified path unless they already exist.2CreateDirectoryDirectorySecurity(String)Creates all the directories in the specified path, unless the already exist, applying the specified Windows security.3Delete(String)Deletes an empty directory from a specified path.4DeleteBoolean(String)Deletes the specified directory and, if indicated, any subdirectories and files in the directory.5EnumerateDirectories(String)Returns an enumerable collection of directory names in a specified path.6EnumerateDirectories(String, String)Returns an enumerable collection of directory names that match a search pattern in a specified path.To get the directory names, use the EnumerateDirectories method. ... Read More