inheritance

问题 I'm trying to access the member variable x in struct Top using a Bottom object. The code is the following: #include <cstdio> struct Top { public: int x = 1; }; struct Left : public Top { int x = 2; }; struct Right : public Top { int x = 3; }; struct Bottom : public Left, public Right { int x = 4; }; int main() { Bottom b; std::printf("value: %d\n", b.Left::Top::x); return 0; } This gives the following error using gcc 4.8: main.cpp: In function 'int main()': main.cpp:27:45: error: 'Top' is an

问题 I'm trying to access the member variable x in struct Top using a Bottom object. The code is the following: #include <cstdio> struct Top { public: int x = 1; }; struct Left : public Top { int x = 2; }; struct Right : public Top { int x = 3; }; struct Bottom : public Left, public Right { int x = 4; }; int main() { Bottom b; std::printf("value: %d\n", b.Left::Top::x); return 0; } This gives the following error using gcc 4.8: main.cpp: In function 'int main()': main.cpp:27:45: error: 'Top' is an

问题 As far as In understand he getS method from child class BB overrides the same method from the parent class AA . Yet although both classes have initialized the field s which is returned by getS it's printed as null . Why is this happening? This is the code: public class AA { public String getS() { return s; } private String s = "hello1"; public AA() { System.out.println(service() + getS()); } public static String service() { return "A service "; } } public class BB extends AA { private String

问题 As far as In understand he getS method from child class BB overrides the same method from the parent class AA . Yet although both classes have initialized the field s which is returned by getS it's printed as null . Why is this happening? This is the code: public class AA { public String getS() { return s; } private String s = "hello1"; public AA() { System.out.println(service() + getS()); } public static String service() { return "A service "; } } public class BB extends AA { private String

问题 As far as In understand he getS method from child class BB overrides the same method from the parent class AA . Yet although both classes have initialized the field s which is returned by getS it's printed as null . Why is this happening? This is the code: public class AA { public String getS() { return s; } private String s = "hello1"; public AA() { System.out.println(service() + getS()); } public static String service() { return "A service "; } } public class BB extends AA { private String

问题 As far as In understand he getS method from child class BB overrides the same method from the parent class AA . Yet although both classes have initialized the field s which is returned by getS it's printed as null . Why is this happening? This is the code: public class AA { public String getS() { return s; } private String s = "hello1"; public AA() { System.out.println(service() + getS()); } public static String service() { return "A service "; } } public class BB extends AA { private String

问题 I have 16 methods that take two parameters, and each of the two parameters can be either an 'Insertion' or a 'Deletion', both of which implement IFragment. I also have four helper functions like this: static IFragment[] IntroduceAntecedent(IFragment on, IFragment item) { bool onIsInsertion = on is Insertion; bool itemIsInsertion = item is Insertion; if (onIsInsertion) { if (itemIsInsertion) { return IntroduceAntecedent((Insertion) on, (Insertion) item); } else { return IntroduceAntecedent(

问题 I have 16 methods that take two parameters, and each of the two parameters can be either an 'Insertion' or a 'Deletion', both of which implement IFragment. I also have four helper functions like this: static IFragment[] IntroduceAntecedent(IFragment on, IFragment item) { bool onIsInsertion = on is Insertion; bool itemIsInsertion = item is Insertion; if (onIsInsertion) { if (itemIsInsertion) { return IntroduceAntecedent((Insertion) on, (Insertion) item); } else { return IntroduceAntecedent(

问题 I have several pairs of structs for which the fields of one is a perfect superset of the other. I'd like to simulate some kind of inheritance so I don't have to have separate cases for each struct since that would almost double my code. In a language like C, I could simulate inheritance of fields with something like this: struct A { int a; }; struct B { struct A parent; int b; }; main() { struct B test1; struct A *test2 = &test1; test2->a = 7; } I want to do something like this in Rust. I

问题 This question already has answers here : Declaring a new instance of a class in C# (2 answers) Closed 9 days ago . Is there a way to instantiate a class that derives from MonoBehaviour such as the example bellow without getting the warning: "You are trying to create a MonoBehaviour using the 'new' keyword. This is not allowed. MonoBehaviours can only be added using AddComponent(). Alternatively, your script can inherit from ScriptableObject or no base class at all" Example: public class