C Sharp中的继承

Question

我是C＃的新手，请你解释一下这句话的错误bigderive c = new bigbase();

Answer 1

看起来像这样：跑车是一辆带有一些额外功能的车。如果您将跑车存放在汽车现场，我们所知道的是：它是一辆汽车。但它是100％的汽车。

如果你试图将汽车存放在运动车上，我们无法确定它实际上是一辆跑车。这就是为什么这种说法是错误的。

如果您说bigbase c = new bigderivce()可行，那么bigderive 100％肯定至少bigbase +一些额外内容。

一个例子：

class Car {
  public void drive() { 
    // do stuff
  }
}
class SportsCar : Car {
  public void driveFaster() {

  }
}

Car car1 = new SportsCar();
car1.driveFast(); // this won't compile, because a Car has no driveFast() method by definition

SportsCar car2 = new SportsCar();
car2.driveFast(); // this works

SportsCar car3 = new Car(); // let's assume this compile
car3.driveFast(); // which method of Car would be called now? car3 is a Car, which has no driveFast() method by declaration.