Question

I want to know, if I have a class named Test, what’s the difference below

Test test = new Test();
Test newTest = test;
Test newTest2 = test.Clone();

What’s the different between newTest and newTest2?
Anyone can help?
Thanks in advance!

Answer 1

When you assign the instance, if Test is a class, you’re actually copying the reference, but test and newTest will both point to the same instance in memory.

This means that both variables point to the same object:

Test test = new Test();
test.Foo = 24;
Test newTest = test;
newTest.Foo = 42;
Console.WriteLine(test.Foo); // Prints 42!

Clone(), on the other hand, typically is used to indicate a copy of the object itself, which means that test and newTest2 would point to different objects, so the above wouldn’t happen.

Note that, if test is a struct (value type), then a direct assignment is effectively a full (shallow) copy of the object, by value.