Notice especially the results for car2 , which probably are not what you expected. The type of the object is ConvertibleCar , but DescribeCar does not access the version of ShowDetails that is defined in the ConvertibleCar class because that method is declared with the new modifier, not the override modifier. As a result, a ConvertibleCar object displays the same description as a Car object. Contrast the results for car3 , which is a Minivan object.
In this case, the ShowDetails method that is declared in the Minivan class overrides the ShowDetails method that is declared in the Car class, and the description that is displayed describes a minivan.
TestCars2 creates a list of objects that have type Car. The values of the objects are instantiated from the Car , ConvertibleCar , and Minivan classes.
DescribeCar is called on each element of the list. The following code shows the definition of TestCars2. The following output is displayed. Notice that it is the same as the output that is displayed by TestCars1. Conversely, car3 calls the ShowDetails method from the Minivan class in both cases, whether it has type Minivan or type Car.
Methods TestCars3 and TestCars4 complete the example. The following code defines these two methods. The methods produce the following output, which corresponds to the results from the first example in this topic. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services.
Privacy policy. Skip to main content. I tried with both. For GCC , You don't need to split the functions into separate. We can see in above example, both func2 in the same file as func1 and func3 in a separate file can be overridden.
To override a function, when compiling its consumer 's translation unit , you need to specify that function as weak. That will record that function as weak in the consumer.
Here I removed the override version of func3. I did this because I want to fall back to the original func3 implementation in the func3. I still use Makefile1 to build. The build is OK. But a runtime error happens as below:.
So why? Didn't I add the func3. I tried the same thing with func2 , where I removed the func2 implementation from ovrride. But this time there's no segment fault. So func2 is always brought in with func1. But unfortunately the GCC linker will not check the other. Though it is indeed there. So I must provide an override version in override.
But I still don't know why GCC behaves like this. If someone can explain, please. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Override a function call in C Ask Question. Asked 12 years, 8 months ago. Active 3 months ago. Viewed k times. Improve this question.
A related thread: stackoverflow. Add a comment. Active Oldest Votes. With gcc, under Linux you can use the --wrap linker flag like this: gcc program. Improve this answer. I should've double checked in the man page : — codelogic.
I'm disappointed that ld on Mac OS X doesn't support the --wrap flag. Use a compile-time flag for controlling interception see updated answer. The overridden base method must be virtual, abstract, or override. Here the base class is inherited in the derived class and the method gfg which has the same signature in both the classes, is overridden.
In C we can use 3 types of keywords for Method Overriding: virtual keyword: This modifier or keyword use within base class method. It is used to modify a method in base class for overridden that particular method in the derived class.
It is used to modify a virtual or abstract method into derived class which presents in base class. Here gfg method takes permission from base class to overriding the method in derived class. To avoid this problem we use virtual and override keyword. Example 2: Method overriding using virtual and override modifiers.
It basically used to access constructors and methods or functions of the base class. The base keyword cannot use within a static method. Base keyword specifies which constructor of the base class should be invoked while creating the instances of the derived class. Use of Base keyword: Call methods or functions of base class from derived class.
Call constructor internally of base class at the time of inheritance. WriteLine "in clssA 'parameterized constructor' invoked" ; Console. Inheritance provides a lot of benefits including code reusability, separation of concerns, cleaner code, extensibility etc.
The use of inheritance and polymorphism has become an integral part of our life as a programmer. Polymorphism is one of the three main concepts of object-oriented programming, the other two being Encapsulation and Inheritance. Polymorphism is frequently used with inheritance. By polymorphism here, I mean run-time polymorphism or method overriding.
Compile time polymorphism or method overloading does not require inheritance. Method overriding is a feature that allows an object of a base class to call the methods with the same name, parameters, and return type of a base class as well as derived class based on the instance of the class it points to. For example - I have a base class Fruit with the function Details. There is another class Mango which inherits Fruit but also has a function named Details. As per the overriding principle, an object of Fruit can call Details of Fruit, if it stores the instance of Fruit.
The object of Fruit can call the method- Details of class Mango, if it stores the instance of class Mango. But practically, to achieve this, we may need to use a couple of keywords and we are going to check them out.
We use these two keywords to achieve the overriding functionality mentioned above. We can have a better understanding if we do it with some samples. I have added a class named Inheritance to the project. Open the Overriding. The derived class inherits from the Base class. Then, add a method Function1 to the Base class as below. You can notice one thing that the compiler raises warning that it hides the Base.
Function1 and if that is intended, you can add a new keyword. You can build the project. You will see that despite having this compiler warning, the project gets compiled successfully.
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