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The physical level describes complex low-level data structures in detail. Logical level: The next higher level of abstraction describes what data the database stores, and what relationships exist among those data. The logical level thus describes an entire database in terms of a small number of relatively simple structures.
Common data structures and their usage Data Structure Definition Usage Array: A fixed-size collection of elements of the same data type, accessible by indices. General-purpose storage and retrieval, basis of many more complex structures. List: An abstract data type that represents a sequence of values, where the same value may occur more than once.
The basic mechanism of control abstraction is a function or subroutine. Data abstractions include various forms of type polymorphism. More elaborate mechanisms that may combine data and control abstractions include: abstract data types, including classes, polytypism etc. The quest for richer abstractions that allow less duplication in complex ...
A data structure known as a hash table.. In computer science, a data structure is a data organization and storage format that is usually chosen for efficient access to data. [1] [2] [3] More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can be applied to the data, [4] i.e., it is an algebraic structure about data.
Data abstraction is a design pattern in which data are visible only to semantically related functions, to prevent misuse. The success of data abstraction leads to frequent incorporation of data hiding as a design principle in object-oriented and pure functional programming.
The "generic programming" paradigm is an approach to software decomposition whereby fundamental requirements on types are abstracted from across concrete examples of algorithms and data structures and formalized as concepts, analogously to the abstraction of algebraic theories in abstract algebra. [6] Early examples of this programming approach ...
In class-based programming, a factory is an abstraction of a constructor of a class, while in prototype-based programming a factory is an abstraction of a prototype object. A constructor is concrete in that it creates objects as instances of one class, and by a specified process (class instantiation), while a factory can create objects by instantiating various classes, or by using other ...
Example: abstraction of integer sets (red) to sign sets (green) Let be an ordered set, called concrete set, and let ′ be another ordered set, called abstract set. These two sets are related to each other by defining total functions that map elements from one to the other.