我见过很多人使用以下代码:

Type t = obj1.GetType();
if (t == typeof(int))
    // Some code here

但我知道你也可以这样做:

if (obj1.GetType() == typeof(int))
    // Some code here

或者这个:

if (obj1 is int)
    // Some code here

就我个人而言,我觉得最后一个是最干净的,但我有什么遗漏吗?哪一个最好用,还是个人喜好?


当前回答

if (c is UserControl) c.Enabled = enable;

其他回答

我有一个要比较的Type属性,无法使用它(例如my_Type是_BaseTypetoLookFor),但我可以使用这些属性:

base_type.IsInstanceOfType(derived_object);
base_type.IsAssignableFrom(derived_type);
derived_type.IsSubClassOf(base_type);

请注意,在比较相同类型时,IsInstanceOfType和IsAssignableFrom返回true,其中IsSubClassOf将返回false。IsSubclassOf不适用于接口,而其他两个则适用

public class Animal {}
public interface ITrainable {}
public class Dog : Animal, ITrainable{}

Animal dog = new Dog();

typeof(Animal).IsInstanceOfType(dog);     // true
typeof(Dog).IsInstanceOfType(dog);        // true
typeof(ITrainable).IsInstanceOfType(dog); // true

typeof(Animal).IsAssignableFrom(dog.GetType());      // true
typeof(Dog).IsAssignableFrom(dog.GetType());         // true
typeof(ITrainable).IsAssignableFrom(dog.GetType()); // true

dog.GetType().IsSubclassOf(typeof(Animal));            // true
dog.GetType().IsSubclassOf(typeof(Dog));               // false
dog.GetType().IsSubclassOf(typeof(ITrainable)); // false

一切都不同。

typeof采用类型名(您在编译时指定)。GetType获取实例的运行时类型。如果实例在继承树中,则返回true。

实例

class Animal { } 
class Dog : Animal { }

void PrintTypes(Animal a) { 
    Console.WriteLine(a.GetType() == typeof(Animal)); // false 
    Console.WriteLine(a is Animal);                   // true 
    Console.WriteLine(a.GetType() == typeof(Dog));    // true
    Console.WriteLine(a is Dog);                      // true 
}

Dog spot = new Dog(); 
PrintTypes(spot);

T型怎么样?它是否也在编译时解决?

对T始终是表达式的类型。请记住,泛型方法基本上是一组具有适当类型的方法。例子:

string Foo<T>(T parameter) { return typeof(T).Name; }

Animal probably_a_dog = new Dog();
Dog    definitely_a_dog = new Dog();

Foo(probably_a_dog); // this calls Foo<Animal> and returns "Animal"
Foo<Animal>(probably_a_dog); // this is exactly the same as above
Foo<Dog>(probably_a_dog); // !!! This will not compile. The parameter expects a Dog, you cannot pass in an Animal.

Foo(definitely_a_dog); // this calls Foo<Dog> and returns "Dog"
Foo<Dog>(definitely_a_dog); // this is exactly the same as above.
Foo<Animal>(definitely_a_dog); // this calls Foo<Animal> and returns "Animal". 
Foo((Animal)definitely_a_dog); // this does the same as above, returns "Animal"
if (c is UserControl) c.Enabled = enable;

我发现,通过以下方法检查某个事物的类型是否等于某个事物:

variableName.GetType()==typeof(int)

我更喜欢的是

也就是说,如果你使用的是is,你很可能没有正确使用继承。

假设那个人:实体,那个动物:实体。Feed是Entity中的一种虚拟方法(让Neil开心)

class Person
{
  // A Person should be able to Feed
  // another Entity, but they way he feeds
  // each is different
  public override void Feed( Entity e )
  {
    if( e is Person )
    {
      // feed me
    }
    else if( e is Animal )
    {
      // ruff
    }
  }
}

相当地

class Person
{
  public override void Feed( Person p )
  {
    // feed the person
  }
  public override void Feed( Animal a )
  {
    // feed the animal
  }
}