String stands for System.String whereas string is an alias in C# for System.String −For examplestring str = "Welcome!";It’s not essential, but generally String is used when you work with classes.string str = String.Format("Welcome! {0}!", user);Since the string is an alias for System. String. The alias for other datatypes are −Exampleobject: System.Object string: System.String bool: System.Boolean float: System.Single double: System.Double decimal: System.Decimal byte: System.Byte sbyte: System.SByte short: System.Int16 ushort: System.UInt16 int: System.Int32 uint: System.UInt32 long: System.Int64 ulong: System.UInt64 char: System.Char

To copy a collection to an array, firstly set it −List < string > list1 = new List < string > (); list1.Add("Car"); list1.Add("Bus"); list1.Add("Motorbike"); list1.Add("Train");Now declare a string array and use the CopyTo() method to copy −string[] arr = new string[20]; list1.CopyTo(arr);Let us see the complete code to copy collection to array −Exampleusing System; using System.Collections.Generic; using System.Linq; public class Demo {    public static void Main() {       List < string > list1 = new List < string > ();       list1.Add("Car");       list1.Add("Bus");       list1.Add("Motobike");       ... Read More

StringReader and StringWriter derive from TextReader and TextWriterStringWriter is used for writing into a string buffer. It implements a TextWriter for writing information to a string.For StringWriter −ExampleStringWriter sWriter = new StringWriter(); while(true) {    myChar = strReader.Read();    if(myChar == -1) break;    convertedChar = Convert.ToChar(myChar);    if(convertedChar == '.') {       strWriter.Write(".");       sReader.Read();       sReader.Read();    }else {       sWriter.Write(convertedChar);    } } }StringReader to read a string −ExampleStringBuilder sbuilder = new StringBuilder(); // append sbuilder.AppendLine("Line one characters"); sbuilder.AppendLine("Line two characters"); sbuilder.AppendLine("Line three characters"); // ... Read More

The 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 be implemented differently in different inherited class and the call to these functions will be decided at runtime.The following is a virtual functionpublic virtual int area() { }Here is an example showing how to work with virtual functions −Exampleusing System; namespace PolymorphismApplication {    class Shape {       protected int width, height;           ... Read More

Non-static classes can be instantiated, whereas static classes cannot be instantiated i.e. you cannot use the new keyword to create a variable of the class type.Non-static classes can have instance method and static methods.Access the members of a static class by using the class name itself, whereas Static class is sealed.Example of non-static class −public class CalculateExample of static class −public static class Calculate

The FizzBuzz problem states that −Display "Fizz" instead of the number for each multiple of 3,Display "Buzz", instead of the number for each multiple of 5.Display "FizzBuzz", instead of the number for each multiple of 5 & 3Let us see how to implement the above using C# −Exampleusing System; class Demo {    static void Main(String[] args) {       for(int i=1;i

The following are the types of expressions in C# −lvalue − An expression that is an lvalue may appear as either the left-hand or right-hand side of an assignment.rvalue − An expression that is an rvalue may appear on the right- but not left-hand side of an assignment.Variables are lvalues and hence they may appear on the left-hand side of an assignment. Numeric literals are rvalues and hence they may not be assigned and cannot appear on the left-hand side.Here is a valid C# statement −int a = 100:

The ArrayCopyTo() method copies all the elements of the current one-dimensional Array to the specified one-dimensional Array starting at the specified destination Array index. The index is specified as a 32-bit integer.The CopyTo() method in C# is used to copy elements of one array to another array. In this method, you can set the starting index from where you want to copy from the source array.The following is an example showing the usage of CopyTo(, ) method of array class in C# −Exampleusing System; class Program {    static void Main() {       int[] arrSource = new ... Read More

To swap two numbers, work with the following logic.Set two variables for swapping −val1 = 100; val2 = 200;Now perform the following operation for swap −val1 = val1 + val2; val2 = val1 - val2; val1 = val1 - val2;The following is the code −Exampleusing System; namespace Demo {    class Program {       static void Main(string[] args) {          int val1,val2;          val1 = 100;          val2 = 200;          Console.WriteLine("Values before swap...");          Console.WriteLine(val1.ToString());          Console.WriteLine(val2.ToString());          val1 = val1 + val2;          val2 = val1 - val2;          val1 = val1 - val2;              Console.WriteLine("Values after swap...");          Console.WriteLine(val1.ToString());          Console.WriteLine(val2.ToString());          Console.ReadLine();       }    } }

VirtualThe virtual keyword allows a class to be overridden. For overriding a parent class method in the child class, declare the parent class method as virtual.SealedWhen a class is declared sealed, it cannot be inherited, abstract classes cannot be declared sealed.To prevent being overridden, use the sealed in C#. 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.public sealed override void getResult() { }NewUse the new keyword to hide the base class method ... Read More