C# 10: File-Scoped Namespaces

Vertical whitespace is valuable. The “block-scoped” namespace syntax indents every single class in your project, wasting 4 spaces of indentation. C# 10 introduces File-Scoped namespaces to reclaim that space.

Comparison

// Old C# 9
namespace MyCompany.MyApp
{
    public class MyClass 
    {
        // 4 spaces indented
    }
}

// New C# 10
namespace MyCompany.MyApp; // Ends with semi-colon

public class MyClass
{
    // Zero indentation!
}

Key Takeaways

• Use `dotnet format` or IDE cleanup to convert your entire solution automatically.
• You cannot mix file-scoped and block-scoped namespaces in the same file.