Programming

Front 1

What is a namespace?

Back 1

For many programming languages, a namespace is a context for identifiers. In an operating system, an example of namespace is a directory. It contains items which must have unique names.

Front 2

What is serialization?

Back 2

In computer science, in the context of data storage and transmission, serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file, a memory buffer, or transmitted across a network connection link to be "resurrected" later in the same or another computer environment.

Front 3

What is managed code?

Back 3

Managed code is a differentiation created by Microsoft to identify computer program code that requires and will only execute under the "management" of a Common Language Runtime virtual machine (resulting in Bytecode).

Front 4

What is a constructor?

Back 4

In object-oriented programming, a constructor (sometimes shortened to ctor) in a class is a special type of subroutine called when an object is created, either when it is declared (statically constructed on the stack, possible in C++ but not in Java and other object-oriented languages) or when it is dynamically constructed on the heap through the keyword "new". Its purpose is to prepare the new object for use, often accepting parameters which are used by the constructor to set member variables which are required when the object is first created.

A constructor is similar to an instance method, but it differs from a method in that it never has an explicit return type, it is not inherited (though many languages provide access to the superclass's constructor, e.g. through the super keyword in Java), and usually has different rules for scope modifiers. Constructors are often distinguished by having the same name as the declaring class. Their responsibility is to initialize the object's data members and to establish the invariant of the class, failing if the invariant isn't valid. A properly written constructor will leave the object in a valid state. Immutable objects must be initialized in a constructor.

Front 5

What is polling?

Back 5

Polling, or polled operation, in computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity. Polling is most often used in terms of input/output (I/O), and is also referred to as polled I/O or software driven I/O.

Polling is sometimes used synonymously with busy-wait polling (Busy waiting). In this situation, when an I/O operation is required the computer does nothing other than check the status of the I/O device until it is ready, at which point the device is accessed. In other words the computer waits until the device is ready. Polling also refers to the situation where a device is repeatedly checked for readiness, and if it is not the computer returns to a different task. Although not as wasteful of CPU cycles as busy-wait, this is generally not as efficient as the alternative to polling, interrupt driven I/O.

Front 6

What is a message pump?

Back 6

Message pumps are said to 'pump' messages from the program's message queue (assigned and usually owned by the underlying operating system) into the program for processing.

Front 7

What are access specifiers?

Back 7

Access specifiers specify constraints on who can access which class members. Some access specifiers may also control how classes inherit such constraints. Their primary purpose is to separate the interface of a class with its implementation.

Front 8

What is a private class?

Back 8

Private restricts the access to the class itself. Only methods that are part of the same class can access private members.

Front 9

What is a protected class?

Back 9

Protected allows the class itself and all its subclasses to access the member.

Front 10

What is a public class?

Back 10

Public means that any code can access the member by its name.

Front 11

What is a class?

Back 11

A class usually represents a noun, such as a person, place or (possibly quite abstract) thing - it is a model of a concept within a computer program. Fundamentally, it encapsulates the state and behavior of the concept it represents. It encapsulates state through data placeholders called attributes (or member variables or instance variables); it encapsulates behavior through reusable sections of code called methods.