Does C support multiple inheritance

Question

A colleague and I are having a bit of an argument over multiple inheritance   I m saying it s not supported and he s saying it is   So  I thought that I d ask the brainy bunch on the net

User · Answer

Multiple inheritance is not supported in C#.

But if you want to "inherit" behavior from two sources why not use the combination of:

Composition
Dependency Injection

There is a basic but important OOP principle that says: "Favor composition over inheritance".

You can create a class like this:

public class MySuperClass
{
    private IDependencyClass1 mDependency1;
    private IDependencyClass2 mDependency2;

    public MySuperClass(IDependencyClass1 dep1, IDependencyClass2 dep2)
    {
        mDependency1 = dep1;
        mDependency2 = dep2;
    }

    private void MySuperMethodThatDoesSomethingComplex()
    {
        string s = mDependency1.GetMessage();
        mDependency2.PrintMessage(s);
    }
}

As you can see the dependecies (actual implementations of the interfaces) are injected via the constructor. You class does not know how each class is implemented but it knows how to use them. Hence, a loose coupling between the classes involved here but the same power of usage.

Today's trends show that inheritance is kind of "out of fashion".

User · Answer

Nope  use interfaces instead

User · Answer

It does not allow it  use interface to achieve it   Why it is so   Here is the answer  It s allowed the compiler to make a very reasoned and rational decision that was always going to consistent about what was inherited and where it was inherited from so that when you did casting and you always know exactly which implementation you were dealing with

User · Answer

In generally  you can   t do it   Consider these interfaces and classes   public class A         public class B     public class C      public interface IA     public interface IB       You can inherit multiple interfaces   class A   B  IA  IB        Inherits any single base class  plus multiple interfaces      But you can   t inherit multiple classes   class A   B  C  IA  IB          Inherits multiple base classes  plus multiple interfaces

User · Answer

C  3 5 or below does not support the multiple inheritance  but C  4 0 could do this by using  as I remembered  Dynamics

User · Answer

Actually  it depends on your definition of inheritance    you can inherit implementation  members  i e  data and behavior  from a single class  but  you can inherit interfaces from multiple  well  interfaces    This is not what is usually meant by the term  inheritance   but it is also not entirely unreasonable to define it this way

User · Answer

You cannot do multiple inheritance in C  till 3 5  I dont know how it works out on 4 0 since I have not looked at it  but  tbischel has posted a link which I need to read   C  allows you to do  multiple-implementations  via interfaces which is quite different to  multiple-inheritance   So  you cannot do   class A    class B    class C   A  B     But  you can do   interface IA   interface IB    class C   IA  IB     HTH

User · Answer

As an additional suggestion to what has been suggested  another clever way to provide functionality similar to multiple inheritance is implement multiple interfaces BUT then to provide extension methods on these interfaces  This is called mixins  It s not a real solution but it sometimes handles the issues that would prompt you to want to perform multiple inheritance

User · Answer

Like Java  which is what C  was indirectly derived from   C  does not support multiple inhertance   Which is to say that class data  member variables and properties  can only be inherited from a single parent base class  Class behavior  member methods   on the other hand  can be inherited from multiple parent base interfaces   Some experts  notably Bertrand Meyer  considered by some to be one of the fathers of object-oreiented programming   think that this disqualifies C   and Java  and all the rest  from being a  true  object-oriented language

User · Answer

Sorry  you cannot inherit from multiple classes  You may use interfaces or a combination of one class and interface s   where interface s  should follow the class name in the signature  interface A     interface B     class Base     class AnotherClass      Possible ways to inherit  class SomeClass   A  B        from multiple Interface s  class SomeClass   Base  B        from one Class and Interface s   This is not legal  class SomeClass   Base  AnotherClass

User · Answer

I recently somehow got to the same mindset  inheriting two classes into a class and ended up on this page  even though i know better  and would like to keep reference to the solution i found perfect in this scenario  without enforcing implementation of interfaces  My solution to this problem would be splitting up your data into classes that make sense   public class PersonAddressSuper       public PersonBase Person   get  set        public PersonAddress Address   get  set         public class PersonBase               public int ID   get  set            public string Name   get  set              public class PersonAddress               public string StreetAddress   get  set            public string City   get  set              Later on in your code  you could use it like this   Include Both Parts  Base  amp  Address  PersonAddressSuper PersonSuper   new PersonAddressSuper    PersonSuper PersonAddress StreetAddress    PigBenis Road 16     Base Only   PersonAddressSuper PersonBase PersonBase   new PersonAddressSuper PersonBase    PersonBase Name    Joe Shmoe     Address Only   PersonAddressSuper PersonAddress PersonAddress   new PersonAddressSuper PersonAddress    PersonAddress StreetAddress    PigBenis Road 16

User · Answer

You can t inherit multiple classes at a time  But there is an options to do that by the help of interface  See below code   interface IA       void PrintIA       class  A IA       public void PrintIA                 Console WriteLine  PrintA method in Base Class A             interface IB       void PrintIB       class B   IB       public void PrintIB                 Console WriteLine  PrintB method in Base Class B             public class AB  IA  IB       A a   new A        B b   new B         public void PrintIA                a PrintIA               public void PrintIB                 b PrintIB              you can call them as below  AB ab   new AB    ab PrintIA    ab PrintIB

User · Answer

C  does not support multiple inheritance of classes  but you are permitted to inherit implement any number of interfaces   This is illegal  B  C  D  amp  E are all classes   class A   B  C  D  E       This is legal  IB  IC  ID  amp  IE are all interfaces   class A   IB  IC  ID  IE       This is legal  B is a class  IC  ID  amp  IE are interfaces   class A   B  IC  ID  IE       Composition over inheritance is a design pattern that seems to be favorable even in languages that support multiple inheritance

User · Answer

Simulated Multiple Inheritance Pattern http   www codeproject com KB architecture smip aspx

User · Answer

You may want to take your argument a step further and talk about design patterns - and you can find out why he d want to bother trying to inherit from multiple classes in c  if he even could

User · Answer

Multiple inheritance allows programmers to create classes that combine aspects of multiple classes and their corresponding hierarchies  For ex  the C   allows you to inherit from more than one class  In C   the classes are only allowed to inherit from a single parent class  which is called single inheritance  But you can use interfaces or a combination of one class and interface s   where interface s  should be followed by class name in the signature   Ex   Class FirstClass     Class SecondClass      interface X     interface Y       You can inherit like the following   class NewClass   X  Y     In the above code  the class  NewClass  is created from multiple interfaces   class NewClass   FirstClass  X     In the above code  the class  NewClass  is created from interface X and class  FirstClass

User · Answer

C  does not support multiple inheritance built in   For adding multiple inheritance to languages that does not support it  You can use twin design pattern

[c#] Does C# support multiple inheritance?

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