Check if Two Dictionary Objects are Equal in C#

Last Updated : 01 May, 2025

In C#, a Dictionary<TKey, TValue> is a collection of key-value pairs. When we work with dictionaries, we may need to check if two dictionaries are equal. This means they contain the exact same keys and values.

In this article, we are going to learn how to check dictionary equality both by reference and by value in C#.

Syntax:

public virtual bool Equals (object obj);

Parameter: obj: The object to compare with the current dictionary instance.
Return Type: bool: It returns true, if the current dictionary and the specified object refer to the same instance, otherwise, it returns false.

C# Program to Check Dictionary Equality by Reference

This method checks whether two dictionary variables point to the same object in memory.

Example 1: Checking Reference Equality

// C# program to check reference equality 
// of two dictionaries
using System;
using System.Collections.Generic;

class Geeks {
    public static void Main() {
        
        // Creating a Dictionary 
        Dictionary<string, string> d1 = new Dictionary<string, string>();
        d1.Add("Sweta", "Noida");
        d1.Add("Amiya", "Bengaluru");

        // d1 refers to the same instance as d2
        Dictionary<string, string> d2 = d1;

        // Checking reference equality
        Console.WriteLine(d1.Equals(d2));  
    }
}

Output

True

Example 2: Checking Reference Inequality

// C# program to show Equals returns false 
// for different instances with same content
using System;
using System.Collections.Generic;

class Geeks {
    public static void Main() {
        
        // Creating first dictionary
        Dictionary<string, string> d1 = new Dictionary<string, string>();
        d1.Add("Sweta", "Noida");

        // Creating second dictionary with same content
        Dictionary<string, string> d2 = new Dictionary<string, string>();
        d2.Add("Sweta", "Noida");

        // Content is same, references are different
        Console.WriteLine(d1.Equals(d2));  
    }
}

Output

False

C# Program to Check Dictionary Equality by Value

To compare if two dictionaries have the same key-value pairs, here, we will use LINQ methods like Except().

Example: Value-Based Dictionary Comparison

// C# program to compare dictionary values using LINQ
using System;
using System.Collections.Generic;
using System.Linq;

class Geeks {
    public static void Main() {
        
        // Creating first dictionary
        Dictionary<string, string> d1 = new Dictionary<string, string>() {
            {"Sweta", "Noida"},
            {"Amiya", "Bengaluru"}
        };

        // Creating second dictionary with same 
        // key-value pairs in different order
        Dictionary<string, string> d2 = new Dictionary<string, string>() {
            {"Amiya", "Bengaluru"},
            {"Sweta", "Noida"}
        };

        // Comparing dictionaries by content
        bool areEqual = d1.Count == d2.Count && !d1.Except(d2).Any();

        Console.WriteLine("Are dictionaries equal by value? " + areEqual);  
    }
}

Output

Are dictionaries equal by value? True

Important Points:

Use Equals() to check if two dictionary references point to the same object.
Use value-based comparison logic like Except() and Count() when comparing actual content.
We need to compare both keys and values to determine logical equality.

Check if Two Dictionary Objects are Equal in C#

Kirti_Mangal

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Check if Two Dictionary Objects are Equal in C#

C# Program to Check Dictionary Equality by Reference

C# Program to Check Dictionary Equality by Value

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