Why do these two comparisons have different results?

Question

Why does this code return true:

new Byte() == new Byte()   // returns true 

but this code returns false:

new Byte[0] == new Byte[0] // returns false 

Answer 1

Because new Byte() creates value type, which are compared by value (by default it will return byte with value 0). And new Byte[0] creates array, which is a reference type and compared by reference (and these two instances of array will have different references).

See Value Types and Reference Types article for details.

Answer 2

Bytes are value types in .NET, meaning that the == operator returns true if and only if the two bytes have the same value. This is also known as value equality.

But arrays are reference types in .NET, meaning the == operator returns true if and only if they refer to the same array instance in memory. This is also known as reference equality or identity.

Note that the == operator can be overloaded for both reference and value types. System.String, for example, is a reference type, but the == operator for strings compares each character in the array in sequence. See Guidelines for Overloading Equals() and Operator == (C# Programming Guide).

If you want to test whether the arrays contain exactly the same values (in order) you should consider using Enumerable.SequenceEqual instead of ==.