Why must the base class be specified before interfaces when declaring a derived class?

Question

public interface ITest
{
    int ChildCount { get; set; }
}

public class Test
{
}

public class OrderPool : ITest, Test
{
    public int ChildCount
    {
        ge         


        

Answer 1

it's called syntax

There are conventions that you must follow in order for the compiler to compile the code.

They could have chosen to allow both forms, or just the other way around, but they didn't. The reason is probably clarity : you can define a lot of interfaces and only inherit from one class.

Technically it would have been possible to allow them all in random order, but that would make the code less readable.