What are the new features in C# 12?

Question

Accepted Answer

**C# 12 features** — .NET 8 language improvements.

**1. Primary constructors:**
```csharp
public class Person(string name, int age)
{
    public string Name => name;
}
```

**2. Collection expressions:**
```csharp
int[] numbers = [1, 2, 3];
List<string> names = ["Alice", "Bob"];
```

**3. Spread operator:**
```csharp
int[] merged = [..first, 42, ..second];
```

**4. Default lambda parameters:**
```csharp
var add = (int a, int b = 10) => a + b;
add(5);      // 15
add(5, 3);   // 8
```

**5. Alias any type:**
```csharp
using Point = (int X, int Y);
Point p = (1, 2);
```

**6. Experimental attribute:**
```csharp
[Experimental("MY001", UrlFormat = "...")]
public void ExperimentalMethod() { }
```

C#: What are the new features in C# 12?