// int result = 0; 不需要写在外面了 
if (!int.TryParse(input, out int result))

{

    return null;

}

return result;

[Route("")]

public async Task<IActionResult> Index()

{

    string abc = dada();

    string dada()

    {

        return "a";

    }

}

// Expression-bodied constructor

public ExpressionMembersExample(string label) => this.Label = label;

// Expression-bodied finalizer

~ExpressionMembersExample() => Console.Error.WriteLine("Finalized!");

private string label;

// Expression-bodied get / set accessors.

public string Label

{

    get => label;

    set => this.label = value ?? "Default label";

}