C# 11 will introduce features like parameter null checking, list patterns, static abstracts in interfaces and the field keyword . Use this tag if your question specifically pertains to C# 11 specific features. The C# tag should be used if your question is not specific to C# 11 features.
Questions tagged [c#-11.0]
68 questions
82
votes
3 answers
What is double exclamation mark in C#?
From https://source.dot.net/#System.Private.CoreLib/Hashtable.cs,475:
public virtual bool ContainsKey(object key!!)
It looks like two null-forgiving operators. Is there a document about it?
shingo
- 18,436
- 5
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16
votes
1 answer
What is the purpose of the 'scoped' keyword
While looking at the source code of the new DefaultInterpolatedStringHandler I noticed that the ReadOnlySpan was annotated with the scoped keyword. The only documentation I could find was here. However, I wasn't able to figure what the practical…
Twenty
- 5,234
- 4
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- 67
9
votes
3 answers
EF Core model classes: Use C# 11 `required` modifier on all properties, even on value type properties?
When using the nullable-enable feature in Entity Framework Core model classes, the compiler will emit a lot of CS8618 warning like that:
warning CS8618: Non-nullable property 'Title' must contain a non-null value when exiting constructor. Consider…
eikuh
- 673
- 1
- 9
- 18
8
votes
1 answer
CA1062 is thrown after updating to !! parameter null checking
According to CA1062 null checks are required in externally visible methods like this:
public static double GetLongitude(this Location location)
{
if(location is null)
{
throw new ArgumentNullException(nameof(location));
}
…
Matthias Fuglsang-Damgaard
- 303
- 2
- 15
6
votes
2 answers
C# 11 escape rules for ref parameters: ref int vs Span
Why does the following code not compile in C# 11?
// Example 1 - fails
class C {
public Span M(ref int arg) {
Span span;
span = new Span(ref arg);
return span;
}
}
It produces two compile…
Bartosz
- 461
- 2
- 9
5
votes
2 answers
Write other C# code in an interpolated string?
In C# 11 we can now include newlines in an interpolated string. So we can write code like this:
string pageTitle = "";
string header = $"Header: {
pageTitle switch
{
"" => "No title",
_ => pageTitle
}}";
Is…
DeborahK
- 57,520
- 12
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5
votes
1 answer
Is it possible to auto-implement IEquatable and IComparable in C# 11?
When writing C#, I tend to write a lot of value type objects that implement IEquatable, IComparable, or both.
For the sake of this proposal, let's assume that I'm writing a fictitious struct called Int256 with equatable and comparable value…
Matthew Layton
- 39,871
- 52
- 185
- 313
5
votes
1 answer
Generic math how to cast from INumber to a "concrete" type (int/double/etc)
Suppose we have a generic method which accepts INumber and returns int:
// process val and return as int
static int DoSomething(T val) where T : INumber => ...
How can the T be casted to int.
Guru Stron
- 102,774
- 10
- 95
- 132
5
votes
1 answer
C# 11 - What have we gained by adding IAdditionOperators to this method?
I just upgraded Visual Studio 2022 to .NET7, which includes C# 11. I am interested in trying out the new static abstract interface methods, and so followed the tutorial there.
The article shows how to define Point and Translation records that use…
Avrohom Yisroel
- 8,555
- 8
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- 106
5
votes
2 answers
Why am I getting warnings that analysers are not found?
I created a toy project for checking out the latest .NET 7 (preview-5) and the regex code generation. It worked great, so I applied the same changes to an existing project (not for production, but for personal productivity). For some reason, I’m…
Quirin F. Schroll
- 1,302
- 1
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- 25
4
votes
1 answer
Required init property with backing field gives null warning C# 11
Having a required init property which sets a backing field still gives a null warning.
The below code gives a warning:
Warning CS8618 Non-nullable field '_name' must contain a non-null value when exiting constructor. Consider declaring the field…
Joas
- 1,796
- 1
- 12
- 25
4
votes
1 answer
C# 11 - detect required property by reflection
C# 11 added support for required properties.
public class Example
{
public required string Value { get; set; }
}
How do I detect that the property is declared as required by reflection?
Please note this is a different question from Return a…
Mirek
- 4,013
- 2
- 32
- 47
3
votes
1 answer
Using Numeric literals/constants in Generic Math C# 11
I am working with the new Generic Math System in C# 11, which is cool, but I haven't found a way to use numeric literals or mathematical constants with them.
The following example which calculates the circumference of a circle does not work.
public…
paulmattern
- 33
- 3
3
votes
1 answer
Alternative to the new C# 11 `required` modifier in C# 10 and earlier
.NET 7 and C# 11 introduce a new modifier required. Documentation says:
The required modifier indicates that the field or property it's
applied to must be initialized by all constructors or by using an
object initializer. Any expression that…
bahrep
- 29,961
- 12
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3
votes
3 answers
Can I set SetsRequiredMembers or another attribute for only one member in C# 11?
Consider the following code:
public record Foo
{
public required string A { get; init; }
public required string B { get; init; }
}
public record Bar : Foo
{
public Bar()
{
A = "TEST";
}
}
var bar = new Bar
{
B = "ANOTHER…
Ilya Chernomordik
- 27,817
- 27
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