Pitfalls of Equality

Consider the fallowing example:

SomeClass class1 = new SomeClass();
SomeClass class2 = new SomeClass();

bool result = (class1 == class2);

Due to class1 and class2 are exactly the same, you should expect result == true. However, result is false. The reason is operator (==) actually compares references of the objects, rather the objects itself. In case you want to compare objects, override and/or use ‘Equals’ method. Some points of interest:

• By default, Equals method calls to GetHashCode() method and then compares it.
• string type is immutable, it overrides == operator and inside it calls to actual string comparison.
• Interlocked.CompareExchange method comparing objects by references (!!)
• If anyone cares, in Java operator (==) works in same way