What is the result of initiating members with default! statement in C# .net?

Question

Yes, I tried to google around and found everything possible from null-coalescing operator to default keyword, which everything kind of bypasses (as of now) my curiosity about these statements:

public record Person
{
    public string FirstName { get; init; } = default!;
    public string LastName { get; init; } = default!;
};

The snippet comes from this MS official site.

So while I can try out what this code yelds in runtime record instantiation, can anyone please generally explain what is the beauty and magic behind the default! statements ?

Thank you.

Answer 1

default keyword on it's own says use the default value for this type, in this case a null since string is a reference type.

The ! suffix is the null forgiving operator. It suppresses any warnings about a value potentially being null. Without it in this code, you would receive the following warning which is a feature of nullable reference types:

CS8625: Cannot convert null literal to non-nullable reference type