Dictionary.Keys Property in C#


The Dictionary.Keys property in C# is used to fetch all the keys in the Dictionary.

Syntax

Following is the syntax −

public System.Collections.Generic.Dictionary<TKey, TValue>.KeyCollection Keys { get; }

Example

Let us now see an example to implement the Dictionary.Keys property −

using System;
using System.Collections.Generic;
public class Demo {
   public static void Main(){
      Dictionary<string, string> dict =
      new Dictionary<string, string>();
      dict.Add("One", "Kagido");
      dict.Add("Two", "Ngidi");
      dict.Add("Three", "Devillers");
      dict.Add("Four", "Smith");
      dict.Add("Five", "Warner");
      Console.WriteLine("Count of elements = "+dict.Count);
      Console.WriteLine("
Key/value pairs...");       foreach(KeyValuePair<string, string> res in dict){          Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);       }       Console.Write("
All the keys..
");       Dictionary<string, string>.KeyCollection allKeys =       dict.Keys;       foreach(string str in allKeys){          Console.WriteLine("Key = {0}", str);       }    } }

Output

This will produce the following output −

Count of elements = 5
Key/value pairs...
Key = One, Value = Kagido
Key = Two, Value = Ngidi
Key = Three, Value = Devillers
Key = Four, Value = Smith
Key = Five, Value = Warner
All the keys..
Key = One
Key = Two
Key = Three
Key = Four
Key = Five

Example

Let us now see another example to implement the Dictionary.Keys property −

using System;
using System.Collections.Generic;
public class Demo {
   public static void Main(){
      Dictionary<string, string> dict =
      new Dictionary<string, string>();
      dict.Add("One", "Chris");
      dict.Add("Two", "Steve");
      dict.Add("Three", "Messi");
      dict.Add("Four", "Ryan");
      dict.Add("Five", "Nathan");
      Console.WriteLine("Count of elements = "+dict.Count);
      Console.WriteLine("
Key/value pairs...");       foreach(KeyValuePair<string, string> res in dict){          Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);       }       Console.WriteLine("Value for key three = "+dict["Three"]);       dict["Three"] = "Katie";       Console.WriteLine("Updated value associated with key Three...");       Console.WriteLine(dict["Three"]);       Console.Write("
All the keys..
");       Dictionary<string, string>.KeyCollection allKeys = dict.Keys;       foreach(string str in allKeys){          Console.WriteLine("Key = {0}", str);       }    } }

Output

This will produce the following output −

Count of elements = 5
Key/value pairs...
Key = One, Value = Chris
Key = Two, Value = Steve
Key = Three, Value = Messi
Key = Four, Value = Ryan
Key = Five, Value = Nathan
Value for key three = Messi
Updated value associated with key Three...
Katie
All the keys..
Key = One
Key = Two
Key = Three
Key = Four
Key = Five

Updated on: 12-Nov-2019

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