what is the difference between the keywords default and new

Question

below is a sample class,

public class Loan
{
}

now, what is difference between these below 2 line and what is difference between them?

Loan loan = default(Loan);
Loan loan = new Loan();

Is there preference to use one over other?

Answer 1

default is used for zeroing out values. For reference types, thats null. For value types, that is effectively the same as using new without any arguments. default is great for generics.

new creates an instance of that type, invoking the constructor.

In your example, if I do:

Loan loan = default(Loan);

or in newer versions of C#:

Loan loan = default;

which is logically equivalent to

Loan loan = null;

you will get a null reference exception if you don't construct it:

loan.MakePayment(100); // Throws