null forgiving for Nullable primitive type

[AliRezaBeigy]

As null-forgiving documentation, you can use ! to forgiving null value and give a not nullable type.

For example

class A {
    public string? B;
    public int? C;
}

there is the A class with nullable B and C fields
when i try to use with following code, an issue showns

    var a = new A();
    var b = a.B!; // string
    var bNullable = a.B; // Nullable<string>
    var c= a.C!; // Nullable<int>
    var cNullable = a.C; // Nullable<int>

as you can see, the C field always is Nullable, and null forgiving has not worked

[theunrepentantgeek]

The null-forgiving operator is by design an operator that only exists at compile time.

Transforming int? to int would require the operator to have an effect at runtime - this would be a big change.

[kyoyama-kazusa]

Hello.

Nullable<int> (known as int?) and int aren't a same type, so here a.C you can't use null-forgiving operator ! to declare the not-null state on the property C because you may change the result value from an int? to an int. The only way to get the inner value is int value = a.C!.Value, or also you can use pattern matching: if (a.C is { } value) ....

However, string? and string is a same type with different nullability, so a.B! means the value of the property B is not-null. Therefore the operator can be used on this case.

[jnm2]

If you do, _ = a.C is { } value; specifically, you can't use value without getting a "use of unassigned local variable" error. var value = a.C ?? default; works. It's more idiomatic C# than var value = a.C.GetValueOrDefault(); which is what it compiles to.

[kyoyama-kazusa]

Thanks.