FriendFunction and protected friend function, procedure

Question

Hello all

can anyone answer and explain them with examples please

Q:What is the difference between friend function and protected friend function?

Q: what is the difference between function and procedure?

Vulpes · Answer

I've coded a very simple (and silly) example to, hopefully, make clear the difference between internal and protected internal in C#. First build the following into yourclass.dll: // yourclass.cs using System; public class YourClass { protected internal void YourMethod1() { Console.WriteLine("Hello from YourMethod1"); } internal void YourMethod2() { Console.WriteLine("Hello from YourMethod2"); } } public class HisClass // not derived from YourClass { public void HisMethod() { Console.WriteLine("Hello from HisMethod"); Console.WriteLine("I can call YourMethod1 and YourMethod2 because we're in the same program"); YourClass yc = new YourClass(); yc.YourMethod1(); yc.YourMethod2(); } } Now build the following into myclass.exe by adding a reference to yourclass.dll: // myclass.cs using System; class MyClass : YourClass // inherits from YourClass { static void Main() { MyClass mc = new MyClass(); mc.YourMethod1(); // works fine /* mc.YourMethod2(); // doesn't compile if uncommented */ Console.WriteLine(); HisClass hc = new HisClass(); hc.HisMethod(); Console.ReadKey(); } } When you run myclass.exe the output should be: Hello from YourMethod1 Hello from HisMethod I can call YourMethod1 and YourMethod2 because we're in the same program Hello from YourMethod1 Hello from YourMethod2 Notice that even though MyClass inherits from YourClass, it can't call the internal method YourMethod2 because it's in a different program. However, even though it doesn't inherit from YourClass, the HisClass method can call it because they're in the same program (technically, the same assembly). Both MyClass and HisClass have no problem calling YourMethod1 because it's protected OR internal.

Vulpes · Answer

On your first question, hamida, C# doesn't actually support the 'Friend' keyword - it uses the 'internal' keyword instead. However, the two behave exactly the same. So, 'Protected Friend' in VB.Net is the same as 'protected internal' in C#. Notice also that protected internal is equivalent to protected OR internal. The CLR (and C++/CLI) also supports protected AND internal visibility (i.e. visible only to derived classes within the same program) but this isn't supported by either C# or VB.Net.

Soft Corner · Answer

Hi Hamida, For your 2nd Question, here in forum i found best article Check this out : Differences between procedures and functions

Jaganathan Bantheswaran · Answer

Hi, A friend function is used for accessing the non-public members of a class. A class can allow non-member functions and other classes to access its own private data, by making them friends. Thus, a friend function is an ordinary function or a member of another class. A protected function is still private (inaccessible from outside the class), however it can also be accessed from a subclass which extends the class the function is defined in. 1.Function returns a value, but a procedure may return or may not return a value. 2.Function can take only input aurguments, but procedure may take both input and out put parameters.

Suthish Nair · Answer

Its good to see after a long time multiple posts got Accepted as Answers :). At last this functionality got enabled by the development teams.

hamida khanam · Answer

Hello All Thanks everyone for helping me.You all are superb............. @Vulpes Thanks for making things clear to me.Lot of thanks........

hamida khanam · Answer

Hello All Thanks Jaganathan Bantheswaran i got answer of my ist question but 2nd one is not clear yet. Vulpes my ist question is related with c# and 2nd question is related to SQL

Vulpes · Answer

You don't say which language you're using but it sounds like VB.Net. A Friend method (or function) is a method which is callable from anywhere else within the program but, unlike a Public method, not from outside it. A Protected Friend method is a method which is callable from anywhere else within the program OR from any other class which inherits from the class in which the Protected Friend method is defined. A Function is a method which returns a value. A Sub (or procedure) is a method which does not return a value.

FriendFunction and protected friend function, procedure

Answers (8)