Found 34489 Articles for Programming

How to handle empty collections in C#

Chandu yadav
Updated on 23-Jun-2020 08:08:52

337 Views

To handle empty collections, use the DefaultIfEmpty() method in C#.If an array is empty, then using this method will show the default method instead of displaying an error.Let’s say we have an empty list.List myList = new List();Now, use DefaultIfEmpty() method to display the default value.myList.DefaultIfEmpty();Example Live Demousing System; using System.Linq; using System.Collections.Generic; class Demo {    static void Main() {       List myList = new List();       var res = myList.DefaultIfEmpty();       foreach (var a in res) {          Console.WriteLine(a);       }    } }Output0

C# Program to get distinct element from a sequence

karthikeya Boyini
Updated on 23-Jun-2020 08:08:25

231 Views

Set a sequence and add elements.List ID = new List { 120, 111, 250, 111, 120, 300, 399, 450 };Use Distinct() method to get distinct element from the above list.IEnumerable res = ID.AsQueryable().Distinct();Let us see the complete code.Example Live Demousing System; using System.Linq; using System.Collections.Generic; class Demo {    static void Main() {       List ID = new List { 120, 111, 250, 111, 120, 300, 399, 450 };       // get distinct elements       IEnumerable res = ID.AsQueryable().Distinct();       foreach (int arr in res) {          Console.WriteLine(arr);       }    } }Output120 111 250 300 399 450

C# Program to access first element in a Dictionary

Samual Sam
Updated on 23-Jun-2020 08:09:48

3K+ Views

The following is our Dictionary with some elements −Dictionary d = new Dictionary() {    {1,"Electronics"},    {2, "Clothing"},    {3,"Toys"},    {4,"Footwear"},    {5, "Accessories"} };Now to display the first element, set the key like this.d[1];The above displays the first element.Example Live Demousing System; using System.Collections.Generic; public class Program {    public static void Main() {       Dictionary d = new Dictionary() {          {1,"Electronics"},          {2, "Clothing"},          {3,"Toys"},          {4,"Footwear"},          {5, "Accessories"}       };       foreach (KeyValuePair ele in d) {          Console.WriteLine("Key = {0}, Value = {1}", ele.Key, ele.Value);       }       Console.WriteLine("First element: "+d[1]);    } }OutputKey = 1, Value = Electronics Key = 2, Value = Clothing Key = 3, Value = Toys Key = 4, Value = Footwear Key = 5, Value = Accessories First element: Electronics

Add key-value pair in C# Dictionary

Arjun Thakur
Updated on 03-Nov-2023 21:22:42

25K+ Views

To add key-value pair in C# Dictionary, firstly declare a Dictionary.IDictionary d = new Dictionary();Now, add elements with KeyValuePair.d.Add(new KeyValuePair(1, "TVs")); d.Add(new KeyValuePair(2, "Appliances")); d.Add(new KeyValuePair(3, "Mobile"));After adding elements, let us display the key-value pair.Example Live Demousing System; using System.Collections.Generic; public class Demo {    public static void Main() {       IDictionary d = new Dictionary();       d.Add(new KeyValuePair(1, "TVs"));       d.Add(new KeyValuePair(2, "Appliances"));       d.Add(new KeyValuePair(3, "Mobile"));       d.Add(new KeyValuePair(4, "Tablet"));       d.Add(new KeyValuePair(5, "Laptop"));       d.Add(new KeyValuePair(6, "Desktop"));       d.Add(new KeyValuePair(7, "Hard Drive")); ... Read More

Clear a Hashtable in C#

Chandu yadav
Updated on 23-Jun-2020 08:11:04

383 Views

Clear a Hashtable, using the Clear() method in C#.The following is our Hashtable −Hashtable h = new Hashtable(); h.Add(1, "Amit"); h.Add(2, "Sachin"); h.Add(3, "Rahul");Use the clear method.h.Clear();If you will now try to display the Hashtable, nothing would get display since the Hashtable is empty.Example Live Demousing System; using System.Collections; public class Demo {    public static void Main() {       Hashtable h = new Hashtable();       h.Add(1, "Amit");       h.Add(2, "Sachin");       h.Add(3, "Rahul");       Console.WriteLine("Keys and Values list:");       foreach (var key in h.Keys ) {     ... Read More

ContainsKey() method in C#

karthikeya Boyini
Updated on 23-Jun-2020 08:11:40

248 Views

Set a Hashtable collection and add some elements to it.Hashtable h = new Hashtable(); h.Add(1, "Sam"); h.Add(2, "Jack"); h.Add(3, "Andy"); h.Add(4, "Katie"); h.Add(5, "Beth"); h.Add(6, "Benjamin");Use the ContainsKey() method to check whether a key exists in a Hashtable or not.Let’s check for key 3. It returns True of the key is found.h.ContainsKey(3));Example Live Demousing System; using System.Collections; public class Demo {    public static void Main() {       Hashtable h = new Hashtable();       h.Add(1, "Sam");       h.Add(2, "Jack");       h.Add(3, "Andy");       h.Add(4, "Katie");       h.Add(5, "Beth");   ... Read More

Convert.ToDouble Method in C#

Samual Sam
Updated on 23-Jun-2020 08:12:13

8K+ Views

To convert a specified value to a double-precision floating-point number, use Convert.ToDouble() method.The following is our long value −long[] val = { 340, -200};Now convert it to Double.double result; result = Convert.ToDouble(val);Example Live Demousing System; public class Demo {    public static void Main() {       long[] val = { 340, -200};       double result;       // long to double       foreach (long number in val) {          result = Convert.ToDouble(number);          Console.WriteLine("Converted {0} value to {1}",number, result);       }    } }OutputConverted 340 value to 340 Converted -200 value to -200

C# Program to find a value in a Hashtable

George John
Updated on 23-Jun-2020 08:12:48

231 Views

Set Hahtable collection with elements.Hashtable h = new Hashtable(); h.Add(1, "Jack"); h.Add(2, "Henry"); h.Add(3, "Ben"); h.Add(4, "Chris");Let’s say now you need to find a value, then use the ContainsValue() method.We are finding value “Chris” here −h.ContainsValue(“Chris”);Example Live Demousing System; using System.Collections; public class Demo {    public static void Main() {       Hashtable h = new Hashtable();       h.Add(1, "Jack");       h.Add(2, "Henry");       h.Add(3, "Ben");       h.Add(4, "Chris");       Console.WriteLine("Keys and Values list:");       foreach (var key in h.Keys ) {          Console.WriteLine("Key ... Read More

C# Program to find a key in a Hashtable

karthikeya Boyini
Updated on 23-Jun-2020 08:13:17

415 Views

Set Hashtable collection with elements.Hashtable h = new Hashtable(); h.Add(1, "Jack"); h.Add(2, "Henry"); h.Add(3, "Ben"); h.Add(4, "Chris");Let’s say now you need to find any key, then use the Contains() method. We are finding key 3 here −h.Contains(3);The following is the complete example.Example Live Demousing System; using System.Collections; public class Demo {    public static void Main() {       Hashtable h = new Hashtable();       h.Add(1, "Jack");       h.Add(2, "Henry");       h.Add(3, "Ben");       h.Add(4, "Chris");       Console.WriteLine("Keys and Values list:");       foreach (var key in h.Keys ) ... Read More

Remove an item from a Hashtable in C#

Ankith Reddy
Updated on 23-Jun-2020 08:13:54

617 Views

The following is our Hashtable −Hashtable h = new Hashtable(); h.Add(1, "Jack"); h.Add(2, "Henry"); h.Add(3, "Ben"); h.Add(4, "Chris");To remove an item, use the Remove() method. Here, we are removing the 3rd element.h.Remove(3);Let us see the complete example.Example Live Demousing System; using System.Collections; public class Demo {    public static void Main() {       Hashtable h = new Hashtable();       h.Add(1, "Jack");       h.Add(2, "Henry");       h.Add(3, "Ben");       h.Add(4, "Chris");       Console.WriteLine("Initial list:");       foreach (var key in h.Keys ) {          Console.WriteLine("Key = ... Read More

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