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Frequently Asked Questions

Is a C# interface the same as a C++ abstract class?

Andy Mc's C# FAQ for C++ programmers
No, not quite. An abstract class in C++ cannot be instantiated, but it can (and often does) contain implementation code and/or data members. A C# interface cannot contain any implementation code or data members - it is simply a group of method names & signatures. A C# interface is more like a COM interface than a C++ abstract class.

What is the difference between abstract class and interface?

Java FAQ - Page 7
Latest Answer: hi, Diff b/w abstract class and interface are.. Abstract class can have concrete me... Latest Answer: See the base class(super class) of all classes is Object class.Other wise when u creat a class ,and ...

What are the differences between an interface and an abstract class?

Java Programmer's FAQ
The principal difference is that an abstract class is used when you have a type/subtype relationship. An interface does not imply a type/subtype hierarchy; it merely forces a class to have some methods with a given signature. That allows some other code to rely on being able to call those methods. You want to subclass abstract classes when you are making subtypes that define the abstract behavior. The subclass should have a "kind of" relationship to the superclass.

What is Class C?

no-www FAQ
Class C is the most stringent compliance level. According to no-www, www.example.net is an invalid subdomain. All traffic must go to example.net in order to view the site. Very few sites currently hold this classification, partially because many internet users are not yet savvy enough to drop the www every time. For that reason, this classification is not recommended for sites that serve the general public.

Q9. What is the history of the IEEE POSIX 1003.1 System Application Interface (C API) ?

POSIX.1 FAQ
Historically, POSIX 1003.1 has been the base standard upon which the POSIX family of standards has been built. In keeping with its original focus on the UNIX system, it is aimed at interactive timesharing computing environments. The first edition of IEEE Std 1003.1 was published in 1988. Subsequent editions were published in 1990, 1996 and 2001. The 1990 edition was a revision to the 1988 edition and became the stable base standard onto which further amendments were added.

How can I interface to C / Java?

scheme-faq-standards
Most Schemes support a so-called "foreign function interface" (FFI) to the native language (i.e. the language in which the Scheme interpreter/compiler was implemented). FFIs provide the following features: Calling native code from Scheme The most basic FFIs allow you to write functions/methods following certain conventions and then call these native functions/methods from Scheme.

How do I interface to C++ objects from Python?

Extending/Embedding FAQ
Depending on your requirements, there are many approaches. To do this manually, begin by reading the "Extending and Embedding" document. Realize that for the Python run-time system, there isn't a whole lot of difference between C and C++ -- so the strategy of building a new Python type around a C structure (pointer) type will also work for C++ objects. For C++ libraries, you can look at SIP, CXX, Boost, or Weave. SWIG is a similar automated tool that only supports C libraries.

What is an abstract value?

Larch Frequently Asked Questions
abstract value is a mathematical abstraction of some bits that might exist in your computer. (It's an abstraction in the same sense that a road map of the United States is an abstraction of the geography and roads of the United States.) In a Larch BISL's model of your computer, each variable contains an abstract value.

How does the C++ interface differ from the C interface?

NetCDF FAQ
It provides all the functionality of the C interface (except for the generalized mapped access of ncvarputg() and ncvargetg()) and is somewhat simpler to use than the C interface. With the C++ interface, no IDs are needed for netCDF components, there is no need to specify types when creating attributes, and less indirection is required for dealing with dimensions.

Does C# have its own class library?

Andy Mc's C# FAQ for C++ programmers
Not exactly. The .NET Framework has a comprehensive class library, which C# can make use of. C# does not have its own class library.

Why is ActionForm a base class rather than an interface?

Apache Struts Web Application Framework
The MVC design pattern is very simple to understand but much more difficult to live with. You just need this little bit of Business Logic in the View logic or you need just that little bit of View logic in the Business tier and pretty soon you have a real mess. Making ActionForm a class takes advantage of the single inheritance restriction of Java to it makes it more difficult for people to do things that they should not do.

What must a class do to implement an interface?

JAVA interview questions
It must provide all of the methods in the interface and identify the interface in its implements clause.

Do I need to call super() in the constructor of a class that extends an abstract class?

Java FAQ
No. Since abstract classes don't have constructors it would be a syntax error to call super(). Just implement the constructor of the subclass as if it does not have a parent class.

abstract class may not be declared as final.176. What is the ResourceBundle class?

JAVA interview questions
The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run. The exception propagates up to the next higher level try-catch statement (if any) or results in the program's termination.

How can I implement opaque (abstract) data types in C?

Declarations and Initializations
You can't do this in C. If it's impossible or inconvenient to put all the functions in the same source file, there are two usual solutions: Pick a unique prefix for the names of all functions and global variables in a library or package of related routines, and warn users of the package not to define or use any symbols with names matching that prefix other than those documented as being for public consumption.

What is an Abstract?

FAQ - East Coast Closing and Title
abstract is a history of the title to a particular tract of land. It is not a title! It consist of a summary of the material parts or recorded instruments affecting the title of the real estate. The abstract may be correct but the title imperfect. The abstract is not a guarantee. It is only a record of what has been recorded. It does not judge the correctness of any item it lists. It merely reports them for an examiner to interpret.
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