LINQ | Equality Operator | SequenceEqual

The equality operator is used to check whether the given two sequences are identically equal or not. In LINQ, the equality operation contains only one operator that is known as SequenceEqual. It is used to check whether the given elements in the sequence or collection are equal or not. If the given sequences or collections are equal then it returns true otherwise return false.

• It compares the value and the numbers of elements, if the collection or sequence has primitive data types.
• It checks the references of the objects, if the collection has complex type elements.
• It does not support query syntax in C# and VB.Net languages.
• It support method syntax in both C# and VB.Net languages.
• It present in both the Queryable and Enumerable class.
• It is implemented by using deferred execution.
• You are allowed to use IEqualityComparer class to compare two collections of complex type using SequenceEqual method.

Example 1:

// C# program to check the given
// sequences are equal or not
using System;
using System.Linq;

class GFG {

    static public void Main()
    {

        // Data source
        char[] sequence1 = {'p', 'q', 'r', 's', 'y', 'z'};
        char[] sequence2 = {'p', 'q', 'r', 's', 'y', 'z'};

        // Display the sequences
        Console.WriteLine("Sequence 1 is: ");

        foreach(var s1 in sequence1)
        {
            Console.WriteLine(s1);
        }

        Console.WriteLine("Sequence 2 is: ");

        foreach(var s2 in sequence2)
        {
            Console.WriteLine(s2);
        }

        // Check the given sequences are equal or
        // not Using SequenceEqual function
        var result = sequence1.SequenceEqual(sequence2);
        Console.WriteLine("Given Sequences are equal: {0}", result);
    }
}

Output:

Sequence 1 is: 
p
q
r
s
y
z
Sequence 2 is: 
p
q
r
s
y
z
Given Sequences are equal: True

Example 2:

// C# program to check the names of
// the employee are equal or not
using System;
using System.Linq;
using System.Collections.Generic;

// Employee details
public class Employee1 {

    public int emp_id1
    {
        get;
        set;
    }

    public string emp_name1
    {
        get;
        set;
    }
    public string emp_lang1
    {
        get;
        set;
    }
}

// Employee details
public class Employee2 {

    public int emp_id2
    {
        get;
        set;
    }

    public string emp_name2
    {
        get;
        set;
    }
    public string emp_lang2
    {
        get;
        set;
    }
}

public class GFG {

    // Main method
    static public void Main()
    {
        List<Employee1> emp1 = new List<Employee1>() {

            new Employee1() {emp_id1 = 209, emp_name1 = "Anjita",
                                               emp_lang1 = "C#"},

            new Employee1() {emp_id1 = 210, emp_name1 = "Soniya",
                                                emp_lang1 = "C"},

            new Employee1() {emp_id1 = 211, emp_name1 = "Rohit",
                                            emp_lang1 = "Java"},

        };

        List<Employee2> emp2 = new List<Employee2>() {

            new Employee2() {emp_id2 = 209, emp_name2 = "Anjita",
                                            emp_lang2 = "Scala"},

            new Employee2() {emp_id2 = 210, emp_name2 = "Soniya",
                                           emp_lang2 = "Python"},

            new Employee2() {emp_id2 = 211, emp_name2 = "Rohit",
                                            emp_lang2 = "Ruby"},

        };

        // Query to check the names of
        // the employee are equal or not
        // Using SequenceEqual method
        var res = emp1.Select(e => e.emp_name1).SequenceEqual(emp2.Select(e => e.emp_name2));

        Console.WriteLine(res);
    }
}

Output:

True