Set property as nullable C#-CodePudding

I have seen two approaches to setting a property as nullable. What is the difference between the two approaches? which one is clean?

public string? a { get; set; };
public string b { get; set; } = default!;

Edit 1: Updated code to correct syntax and changed int -> string

CodePudding user response：

You wrote int a?instead of int? a.

The 2 behave very differently here. An int is not nullable, its default value is 0. Therefore you can just use defuslt without the ! . The ! just makes the compiler ignore null check rules. The other creates a real null value.

Lets say we instead had: string? a = null Or string a = default! Which behave almost the same, but their type differs.

In that case the ? nullable reference type is more clean as you dont get rid of the null safety guarantees.

CodePudding user response：

The first approach is correct so to say. You can understand this clearly using snippet as below.

void Main()
{
    var pro = new Pro{
        a = 1,
        //b = 1
    };
    Console.WriteLine(typeof(int));
    Console.WriteLine(typeof(int?));
}
public class Pro {
    public int? a { get; set; }
    public int b { get; set; } = default!;  
}