csharp 试试C＃Nullable。代码可以粘贴在LINQPad中并运行。如果要在Visual Studio或其他IDE中运行，则需要重写它。

Posted 2021-05-12

void Main()
{
	String s = null;
	Console.WriteLine("s is {0}", s ?? "Null");
	
	Animal animal = null;
	Console.WriteLine("Animal is {0}", animal ?? new Animal());
	
	Nullable<int> i = null;
	Console.WriteLine("i is {0}", i ?? default(int));
	Console.WriteLine("i is {0}", i.GetValueOrDefault());
}

// Define other methods and classes here
class Animal {
  private string _name = "Animal";
  
  public Animal() {
  }
  
  public Animal(String name) {
    _name = name;
  }
  
  override
  public String ToString() {
    return _name;
  }
}