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home / developersection / interviews / difference between == and equals() method in c#
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Ravi Vishwakarma
Ravi Vishwakarma

Software Developer

Hi, my self Ravi Vishwakarma. I have completed my studies at SPICBB Varanasi. now I completed MCA with 76% form Veer Bahadur Singh Purvanchal University Jaunpur. SWE @ MindStick | Software Engineer | Web Developer | .Net Developer | Web Developer | Backend Engineer | .NET Core Developer

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1 Answers

Ravi Vishwakarma
Ravi Vishwakarma 07 Jun 2024
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In C#, both the ‘==’ operator and the Equals() method are used to compare, but they work for different purposes and behaviors based on the context.

== Operator:

  1. Purpose: The '==' operator is used to compare the similarity of two objects or values.
  2. Behavior: For reference types, == checks if two references point to the same object in memory by default. However, this behavior can be overridden by implementing the == operator or Equals() method in a custom way.
  3. Usage: It's commonly used for comparing built-in datatype types like integers, and floats, or for comparing reference types where reference equality is significant.

Example -

int a = 5;
int b = 5;
Console.WriteLine(a == b);  // Output: True

string str1 = "hello";
string str2 = "hello";
Console.WriteLine(str1 == str2);  // Output: True (reference equality for strings is overridden)

Equals() Method:

  1. Purpose: The Equals() method is used to compare the similarity of two objects.
  2. Behavior: By default, Equals() compares reference equality for reference types (like ==), but this behavior can be overridden by classes to provide custom comparison logic.
  3. Usage: It's often used for comparing objects where custom equality comparison is required, such as comparing the contents of two string objects.

Example -

string str1 = "hello";
string str2 = "hello";
Console.WriteLine(str1.Equals(str2));  // Output: True

object obj1 = new object();
object obj2 = new object();
Console.WriteLine(obj1.Equals(obj2));  // Output: False (reference equality)

Differences:

  1. Usage: The == operator is used for comparing equality, while the Equals() method is a virtual method provided by the System.Object and can be overridden for custom equality comparison.
  2. Behavior: == typically compares reference equality for reference types unless overridden, whereas Equals() can be customized to compare content equality.
  3. Overriding: While == cannot be overridden directly, Equals() can be overridden in classes to provide custom comparison logic.
  4. Null Handling: == handles null references differently based on the type, while Equals() can handle null references if properly implemented.

In summary, use == for comparing equality where reference equality is significant or for built-in types, and use Equals() for comparing objects where custom equality comparison logic is needed, or when dealing with reference types where reference equality might not be sufficient.

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