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Container (programming)
In computer science, a container is a class or a data structureEntry ''data structure'' in the Encyclopædia Britannica (2009Online entryAccessed 4 Oct 2011. whose instances are collections of other objects. In other words, they store objects in an organized way that follows specific access rules. The size of the container depends on the number of objects (elements) it contains. Underlying (inherited) implementations of various container types may vary in size, complexity and type of language, but in many cases they provide flexibility in choosing the right implementation for any given scenario. Container data structures are commonly used in many types of programming languages. Function and properties Containers can be characterized by the following three properties: * ''access'', that is the way of accessing the objects of the container. In the case of arrays, access is done with the array index. In the case of stacks, access is done according to the LIFO (last in, first o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Theory
In mathematics and theoretical computer science, a type theory is the formal presentation of a specific type system. Type theory is the academic study of type systems. Some type theories serve as alternatives to set theory as a foundation of mathematics. Two influential type theories that have been proposed as foundations are: * Typed λ-calculus of Alonzo Church * Intuitionistic type theory of Per Martin-Löf Most computerized proof-writing systems use a type theory for their foundation. A common one is Thierry Coquand's Calculus of Inductive Constructions. History Type theory was created to avoid paradoxes in naive set theory and formal logic, such as Russell's paradox which demonstrates that, without proper axioms, it is possible to define the set of all sets that are not members of themselves; this set both contains itself and does not contain itself. Between 1902 and 1908, Bertrand Russell proposed various solutions to this problem. By 1908, Russell arrive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priority Queue
In computer science, a priority queue is an abstract data type similar to a regular queue (abstract data type), queue or stack (abstract data type), stack abstract data type. In a priority queue, each element has an associated ''priority'', which determines its order of service. Priority queue serves highest priority items first. Priority values have to be instances of an ordered data type, and higher priority can be given either to the lesser or to the greater values with respect to the given order relation. For example, in Java (programming language), Java standard library, ''PriorityQueues the least elements with respect to the order have the highest priority. This implementation detail is without much practical significance, since passing to the converse relation, opposite order relation turns the least values into the greatest, and vice versa. While priority queues are often implemented using Heap (data structure) , heaps, they are conceptually distinct. A priority queue can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panel (computer Software)
A panel is "a particular arrangement of information grouped together for presentation to users in a window or pop-up". In ISPF, a panel is "a predefined display image that you see on a display screen". In modern multiple-document interface software a panel refers to a particular arrangement of information grouped together and presented to users ''docked'' (''by default)'' in the user interface rather than floating in a window, pop-up or dialog box. A panel graphical control element is commonly packaged as part of a widget toolkit (libraries that contain a collection of graphical control elements) for a graphical user interface. See toolbar and dialog box. References See also * GNOME Panel * Kicker (KDE) *Layout manager *Control panel (computer) Many computer user interfaces use a control panel metaphor to give the user control of software and hardware features. The control panel (computer software), panel consists of multiple settings including display settings, network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Window (computing)
In computing, a window is a Graphical widget, graphical control element. It consists of a visual area containing some of the graphical user interface of the program it belongs to and is framed by a #Window decoration, window decoration. It usually has a rectangular shape that can overlap with the area of other windows. It displays the ''output'' of and may allow ''input'' to one or more Process (computing), processes. Windows are primarily associated with graphical displays, where they can be manipulated with a Pointer (graphical user interfaces), pointer by employing some kind of pointing device. Text-only displays can also support windowing, as a way to maintain multiple independent display areas, such as multiple buffers in Emacs. Text windows are usually controlled by keyboard, though some also respond to the mouse. A graphical user interface (GUI) using windows as one of its main "Interface metaphor, metaphors" is called a windowing system, whose main components are the disp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widget (computing)
A graphical widget (also graphical control element or control) in a graphical user interface is an element of interaction, such as a button or a scroll bar. Controls are software components that a computer user interacts with through direct manipulation to read or edit information about an application. User interface libraries such as Windows Presentation Foundation, Qt, GTK, and Cocoa, contain a collection of controls and the logic to render these. Each widget facilitates a specific type of user-computer interaction, and appears as a visible part of the application's GUI as defined by the theme and rendered by the rendering engine. The theme makes all widgets adhere to a unified aesthetic design and creates a sense of overall cohesion. Some widgets support interaction with the user, for example labels, buttons, and check boxes. Others act as containers that group the widgets added to them, for example windows, panels, and tabs. Structuring a user interface with widget to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widget Toolkit
A widget toolkit, widget library, GUI toolkit, or UX library is a library (computing), library or a collection of libraries containing a set of graphical control elements (called ''widgets'') used to construct the graphical user interface (GUI) of programs. Most widget toolkits additionally include their own Rendering (computer graphics), rendering engine. This engine can be specific to a certain operating system or windowing system or contain back-ends to interface with multiple ones and also with rendering APIs such as OpenGL, OpenVG, or EGL (API), EGL. The look and feel of the graphical control elements can be hard-coded or decoupled, allowing the graphical control elements to be Theme (computing), themed/Skin (computing), skinned. Overview Some toolkits may be used from other languages by employing language bindings. Graphical user interface builders such as e.g. Glade Interface Designer facilitate the authoring of GUIs in a WYSIWYG manner employing a user interface markup la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hash Table
In computer science, a hash table is a data structure that implements an associative array, also called a dictionary or simply map; an associative array is an abstract data type that maps Unique key, keys to Value (computer science), values. A hash table uses a hash function to compute an ''index'', also called a ''hash code'', into an array of ''buckets'' or ''slots'', from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored. A map implemented by a hash table is called a hash map. Most hash table designs employ an Perfect hash function, imperfect hash function. Hash collision, Hash collisions, where the hash function generates the same index for more than one key, therefore typically must be accommodated in some way. In a well-dimensioned hash table, the average time complexity for each lookup is independent of the number of elements stored in the table. Many hash table designs also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-balancing Binary Search Tree
In computer science, a self-balancing binary search tree (BST) is any node-based binary search tree that automatically keeps its height (maximal number of levels below the root) small in the face of arbitrary item insertions and deletions.Donald Knuth. '' The Art of Computer Programming'', Volume 3: ''Sorting and Searching'', Second Edition. Addison-Wesley, 1998. . Section 6.2.3: Balanced Trees, pp.458–481. These operations when designed for a self-balancing binary search tree, contain precautionary measures against boundlessly increasing tree height, so that these abstract data structures receive the attribute "self-balancing". For height-balanced binary trees, the height is defined to be logarithmic O(\log n) in the number n of items. This is the case for many binary search trees, such as AVL trees and red–black trees. Splay trees and treaps are self-balancing but not height-balanced, as their height is not guaranteed to be logarithmic in the number of items. Self-bal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Search Tree
In computer science, a binary search tree (BST), also called an ordered or sorted binary tree, is a Rooted tree, rooted binary tree data structure with the key of each internal node being greater than all the keys in the respective node's left subtree and less than the ones in its right subtree. The time complexity of operations on the binary search tree is Time complexity#Linear time, linear with respect to the height of the tree. Binary search trees allow Binary search algorithm, binary search for fast lookup, addition, and removal of data items. Since the nodes in a BST are laid out so that each comparison skips about half of the remaining tree, the lookup performance is proportional to that of binary logarithm. BSTs were devised in the 1960s for the problem of efficient storage of labeled data and are attributed to Conway Berners-Lee and David_Wheeler_(computer_scientist), David Wheeler. The performance of a binary search tree is dependent on the order of insertion of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linked List
In computer science, a linked list is a linear collection of data elements whose order is not given by their physical placement in memory. Instead, each element points to the next. It is a data structure consisting of a collection of nodes which together represent a sequence. In its most basic form, each node contains data, and a reference (in other words, a ''link'') to the next node in the sequence. This structure allows for efficient insertion or removal of elements from any position in the sequence during iteration. More complex variants add additional links, allowing more efficient insertion or removal of nodes at arbitrary positions. A drawback of linked lists is that data access time is linear in respect to the number of nodes in the list. Because nodes are serially linked, accessing any node requires that the prior node be accessed beforehand (which introduces difficulties in pipelining). Faster access, such as random access, is not feasible. Arrays have better cache ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Array Data Structure
In computer science, an array is a data structure consisting of a collection of ''elements'' (value (computer science), values or variable (programming), variables), of same memory size, each identified by at least one ''array index'' or ''key'', a collection of which may be a tuple, known as an index tuple. An array is stored such that the position (memory address) of each element can be computed from its index tuple by a mathematical formula. The simplest type of data structure is a linear array, also called a one-dimensional array. For example, an array of ten 32-bit (4-byte) integer variables, with indices 0 through 9, may be stored as ten Word (data type), words at memory addresses 2000, 2004, 2008, ..., 2036, (in hexadecimal: 0x7D0, 0x7D4, 0x7D8, ..., 0x7F4) so that the element with index ''i'' has the address 2000 + (''i'' × 4). The memory address of the first element of an array is called first address, foundation address, or base address. Because the mathematical conc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Map (computer Science)
In computer science, an associative array, key-value store, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with ''finite'' domain. It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. The two major solutions to the dictionary problem are hash tables and search trees..Dietzfelbinger, M., Karlin, A., Mehlhorn, K., Meyer auf der Heide, F., Rohnert, H., and Tarjan, R. E. 1994"Dynamic Perfect Hashing: Upper and Lower Bounds". SIAM J. Comput. 23, 4 (Aug. 1994), 738-761. http://portal.acm.org/citation.cfm?id=182370 It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
