Determine if a key exists in a Dictionary in C#

This post will discuss how to determine whether a key exists in a Dictionary in C#.

1. Using `ContainsKey()` method

We can use the ContainsKey() method to determine whether the Dictionary contains an element with the specified key. The following example demonstrates this.

using System;

using System.Collections.Generic;

public class Example

{

public static void Main()

{

Dictionary<string, string> dict = new Dictionary<string, string>

{

{ "key1", "value1" },

{ "key2", "value2" },

{ "key3", "value3" }

};

string key = "key2";

bool keyExists = dict.ContainsKey(key);

if (keyExists) {

Console.WriteLine("{0} exists in map", key);

}

else {

Console.WriteLine("{0} does not exist in map", key);

}

Output: key2 exists in map

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2. Using `Dictionary.TryGetValue()` method

TryGetValue() method returns true if the Dictionary contains an element with the specified key; otherwise, false. This is demonstrated below: