All 10 Modern C# Features (Global Usings, File-Scoped Namespaces, Top-Level Statements) questions
More in Modern C# Features (Global Usings, File-Scoped Namespaces, Top-Level Statements)
What are top-level statements, and how do they simplify a basic C# program's entry point? What is a file-scoped namespace declaration, and how does it reduce indentation compared to a traditional block-scoped namespace? What does the 'ImplicitUsings' project setting (`<ImplicitUsings>enable</ImplicitUsings>`) do automatically? How do required members (C# 11's 'required' keyword) enforce that certain properties MUST be set during object initialization? How do C# 12's collection expressions (`[1, 2, 3]`) provide a unified, type-agnostic syntax for initializing arrays, lists, and spans? How do C# 12 primary constructors interact with dependency injection in ASP.NET Core minimal APIs and controller classes? How does the 'file' access modifier (C# 11) create a type visible ONLY within its own source file, and what problem does this solve for source generators? How do C# 12's default parameter values on LAMBDA expressions work, and what limitation did they remove compared to earlier C# versions? How do C# 11's raw string literals (`"""..."""`) simplify writing strings containing quotes, escape sequences, or multi-line content like JSON or SQL?
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C# › Modern C# Features (Global Usings, File-Scoped Namespaces, Top-Level Statements)

How do global using directives work, and how do you declare one for an entire project?

Intermediate

Answer

Prefixing a 'using' directive with 'global' (either directly in a .cs file, or conventionally in a dedicated GlobalUsings.cs file) makes that namespace available to EVERY file in the project automatically, without needing to repeat the same common 'using' statements (like System, System.Linq) at the top of every single file.
// GlobalUsings.cs
global using System;
global using System.Linq;
global using System.Collections.Generic;

// Any other file in the project can now use List<T>, LINQ, etc. WITHOUT its own 'using' statements
Real-world example Eliminating repetitive boilerplate 'using System; using System.Linq;' lines across every file in a large project.

Common follow-ups: Does the SDK automatically generate any implicit global usings for common namespaces, even without an explicit GlobalUsings.cs file?

Fundamentals
All 10 Modern C# Features (Global Usings, File-Scoped Namespaces, Top-Level Statements) questions