Check whether the Dictionary has the specified key or not in C#



To check whether the Dictionary<TKey,TValue> has the specified key or not, the code is as follows −

Example

 Live Demo

using System;
using System.Collections.Generic;
public class Demo {
   public static void Main() {
      Dictionary<string, string> dict =
      new Dictionary<string, string>();
      dict.Add("One", "John");
      dict.Add("Two", "Tom");
      dict.Add("Three", "Jacob");
      dict.Add("Four", "Kevin");
      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);       }       if (dict.ContainsKey("Three"))          Console.WriteLine("Key found!");       else          Console.WriteLine("Key isn't in the dictionary!");       dict.Clear();       Console.WriteLine("Cleared Key/value pairs...");       foreach(KeyValuePair<string, string> res in dict) {          Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);       }       Console.WriteLine("Count of elements now = "+dict.Count);    } }

Output

This will produce the following output −

Count of elements = 5
Key/value pairs...
Key = One, Value = John
Key = Two, Value = Tom
Key = Three, Value = Jacob
Key = Four, Value = Kevin
Key = Five, Value = Nathan
Key found!
Cleared Key/value pairs...
Count of elements now = 0

Example

Let us see another example −

 Live Demo

using System;
using System.Collections.Generic;
public class Demo {
   public static void Main() {
      Dictionary<string, string> dict = new Dictionary<string, string>();
      dict.Add("One", "John");
      dict.Add("Two", "Tom");
      dict.Add("Three", "Jacob");
      dict.Add("Four", "Kevin");
      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);       }       if (dict.ContainsKey("mykey"))          Console.WriteLine("Key found!");       else          Console.WriteLine("Key isn't in the dictionary!");       dict.Clear();       Console.WriteLine("Cleared Key/value pairs...");       foreach(KeyValuePair<string, string> res in dict) {          Console.WriteLine("Key = {0}, Value = {1}", res.Key, res.Value);       }       Console.WriteLine("Count of elements now = "+dict.Count);    } }

Output

This will produce the following output −

Count of elements = 5
Key/value pairs...
Key = One, Value = John
Key = Two, Value = Tom
Key = Three, Value = Jacob
Key = Four, Value = Kevin
Key = Five, Value = Nathan
Key isn't in the dictionary!
Cleared Key/value pairs...
Count of elements now = 0

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