Top-level code containsįor more information, see the C# Language Specification.
The following table shows what the method signature would look like, using the method name Main in the table for convenience. The signature of the method depends on whether the top-level statements contain the await keyword or the return statement. The name of this method isn't actually Main, it's an implementation detail that your code can't reference directly. The compiler generates a method to serve as the program entry point for a project with top-level statements. For example: string? s = Console.ReadLine() To return an int value when the application ends, use the return statement as you would in a Main method that returns an int. You can call an async method by using await. The args variable is never null but its Length is zero if no command-line arguments were provided. Top-level statements can reference the args variable to access any command-line arguments that were entered. For example: M圜lass.TestMethod() Ĭonsole.WriteLine("Hello World from MyNamespace.M圜lass.MyMethod!") Namespaces and type definitionsĪ file with top-level statements can also contain namespaces and type definitions, but they must come after the top-level statements. Top-level statements are implicitly in the global namespace. If you include using directives, they must come first in the file, as in this example: In a project with top-level statements, you can't use the -main compiler option to select the entry point, even if the project has one or more Main methods. The compiler issues the following warning:ĬS7022 The entry point of the program is global code ignoring 'Main()' entry point. You can write a Main method explicitly, but it can't function as an entry point. Putting top-level statements in more than one file in a project results in the following compiler error:ĬS8802 Only one compilation unit can have top-level statements.Ī project can have any number of additional source code files that don't have top-level statements. A project can have only one file with top-level statements. Only one top-level fileĪn application must have only one entry point. The following sections explain the rules on what you can and can't do with top-level statements. They also make it simpler for new C# programmers to get started learning and writing code.
Top-level statements let you write simple programs for small utilities such as Azure Functions and GitHub Actions. Here's a Program.cs file that is a complete C# program in C# 10: Console.WriteLine("Hello World!") In this case, the compiler generates a class and Main method entry point for the application. Instead, you can use the top-level statements feature to minimize the code you have to write. Starting in C# 9, you don't have to explicitly include a Main method in a console application project.
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