computerscience , a string is a Finite set finite sequence of symbol formal symbols that are chosen from a set mathematics set called an alphabet computerscience alphabet . In computer programming , a string is traditionally a sequence of characters, either as a literal computer programming literal .... Using rope computerscience rope s makes certain string operations, such as insertions, deletions ... strings are very common uses of strings, a string in computerscience may refer generically ... string functions String Functions ComputerScienceString functions are used to manipulate a string ... Rope computerscience Rope Bitstring Improper input validation Incompressible string Empty string ... references Data types DEFAULTSORT StringComputerScience Category Character encoding Category ... Syntactic entities Category Stringcomputerscience ar bg ca Cadena inform tica ... computerscience buffer , along with its ASCII or more modern UTF 8 representation as 8 bit hexadecimal ... represented as code len string code . Even though string functions are very useful to a computer programmer, a computer programmer using these functions should be mindful that a string function in one ... changed, or it may be fixed after creation . A string is generally understood as a data type and is often implemented as a byte or Word computer architecture word Array data structure array that stores a sequence of elements, typically characters, using some character encoding . A string may ... such as byte string , or more general, string of datatype , or datatype string , are sometimes used ... language and or precise datatype used, a variable programming variable declared to be a string ... dynamic allocation to allow it to hold chronologically variable number of elements. When a string appears literally in source code , it is known as a string literal and has a representation that denotes ... . A string or word over is any finite sequence of characters from . For example, if 0, 1 , then 0101 ... more details
striking the piano s keys Science, computers, and mathematics Stringcomputerscience , sequence of symbols or digits in computer programming String literal , the notation for representing a string value within the text of a computer program String searching algorithm strings Unix , a Unix program for finding character strings in binary files string C , a class in the C Standard Library string.h , a header in the C standard library Connection string , a string that specifes information about a data source and the means of connecting to it String theory , a popular grand unified theory String physics , one of the main objects of study in string theory Black string is a higher dimensional more than 4 dimensional generalization of a black hole . Cosmic string , a hypothetical 1 dimensional spatially topological defect in various fields Dirac string , a fictitious one dimensional curve in space, stretching between two magnetic monopoles String graph , an intersection graph of curves in the plane each curve is called a stringString group , in group theory STRING Search Tool for the Retrieval ...Wiktionarypar string Image Spool of string.jpg thumb right A spool of string TOC right String is a flexible piece of rope or twine which is used to tie, bind, or hang other objects. Examples of string use include In musical instruments see below Bow string , for propelling an arrow Drawstring Kite Pullstring String art String bag String bondage String figure , design formed by weaving string around one s fingers Stampede string , a long string usually made from leather or horsehair and typically run half way around the crown of a cowboy hat String or strings may also refer to Musical instruments Strings music , flexible material that provides vibrations in string instruments String instrument , a musical instrument that produces sound through vibrating strings String section , the violins, violas, cellos and double basses of an orchestra, often abbreviated as strings String piano , a pianistic ... more details
Computerscience or computing science abbreviated CS or CompSci designates the science scientific and mathematics mathematical approach in computing . ref Cite doi 10.1145 63238.63239 Computerscience ... author Wegner, P. title Research paradigms in computerscience booktitle Proceedings of the 2nd ... date October 13 15, 1976 publisher IEEE Computer Society Press, Los Alamitos, CA quote Computerscience ..., while others, such as Computer graphics computersciencecomputer graphics , emphasize real ... graphics link Computer graphics computerscience File 3 Tastenmaus Microsoft.jpg 94px alt Microsoft ... interaction div class thumbcaption Computerscience deals with the theoretical foundations of information ... div div History Main History of computerscience The earliest foundations of what would become computerscience predate the invention of the modern digital computer . Machines for calculating fixed numerical ... science broadened to study computation in general. Computerscience began to be established as a distinct ... Cl.cam.ac.uk date accessdate 2011 11 19 ref The world s first computerscience degree program, the Cambridge Diploma in ComputerScience , began at the University of Cambridge Cambridge Computer Lab Computer Laboratory in 1953. The first computerscience degree program in the United States was formed at Purdue University in 1962. ref http www.cs.purdue.edu feature conte.html Computerscience pioneer ... that formed part of the computerscience revolution during this time. IBM short for International Business ... to start the whole process over again . ref name Levy1984 During the late 1950s, the computerscience ... seen significant improvements in the usability and effectiveness of computerscience technology. Modern ... academic discipline, computerscience has made a number of fundamental contributions to science ..., R.L. date March 2000 url http www.cs.cornell.edu cis dean bgu.pdf title ComputerScience Achievements ... science A number of computer scientists have argued for the distinction of three separate paradigms ... more details
primary sources date November 2011 infobox biodatabase title STRING logo Image String home page.png 200px STRING home page description Search Tool for the Retrieval of Interacting Genes Proteins scope ... url http www.string db.org STRING website download http string db.org newstring cgi show download ... biology, STRING Search Tool for the Retrieval of Interacting Genes Proteins is a database and web resource ... C title STRING 8 a global view on proteins and their functional interactions in 630 organisms ..., S and Doerks, T and Kruger, B and Snel, B and Bork, P title STRING 7 recent developments ..., M and Jouffre, N and Huynen, MA and Bork, P title STRING known and predicted protein protein associations ... author von Mering, C and Huynen, M and Jaeggi, D and Schmidt, S and Bork, P and Snel, B title STRING ... author Snel, B and Lehmann, G and Bork, P and Huynen, MA title STRING a web server to retrieve ... 18 pages 3442 4 year 2000 pmid 10982861 doi 10.1093 nar 28.18.3442 pmc 110752 ref The STRING database ... version 9.0 contains information on about 5.2 millions proteins from 1133 species. STRING has been ... 10.1038 nmeth.1283 issue 1 pmc 2613168 ref Image STRING network image.png thumb 300px Protein protein interaction network visualized by STRING. In this view, the color saturation of the edges represents ... predictions can be inspected from different designated views. There are two modes of STRING Protein .... A plug in for cytoscape to use STRING data is available. Another possibility to access data STRING .... Data sources Like many other database that store protein association knowledge STRING imports data ..., STRING also store computationally predicted interactions from i text mining of scientific texts, ii ... Kyoto Encyclopedia of Genes and Genomes . Imported data STRING imports protein association knowledge ... Reflist External links http string db.org STRING site Category Biological databases Category Systems biology de STRING ... more details
Infobox film name The String image The String.jpg caption director Mehdi Ben Attia producer writer Mehdi Ben Attia starring Claudia Cardinale music cinematography editor distributor released Film date 2009 8 29 Angoul me 2010 5 12 France runtime country Film France language Arabic language Arabic br French language French budget The String lang fr Le Fil is a 2009 French film directed by Mehdi Ben Attia . It stars Claudia Cardinale . ref cite web url http www.mymovies.it filmografia ?a 202 title Claudia Cardinale publisher Mymovies.it accessdate December 1, 2010 ref Notably, part of the film was shot in Tunisia , Cardinale s country of birth. References reflist External links IMDb title 1302559 Le fil DEFAULTSORT String Category 2009 films Category French films Category Arabic language films Category French language films Category Films shot in Tunisia 2000s France film stub es La Cadena pel cula fr Le Fil film pl Ni film 2009 ru ... more details
teapot , an iconic model in 3D computer graphics created by Martin Newell computer scientist Martin Newell in 1975. Computer graphics is a sub field of computerscience which studies methods for digitally ... Processing , http www.eg.org events Symposium on Rendering, and Symposium on Computer Animation . As in the rest of computerscience, conference publications in computer graphics are generally more ...dablink This article is about the scientific discipline of computer graphics. For other uses see Computer ... computer graphics three dimensional computer graphics , it also encompasses 2D computer graphics two dimensional graphics and image processing . Overview Computer graphics studies the manipulation .... Computer graphics is often differentiated from the field of visualization graphic visualization , although ... visualization Computer vision Image processing Computational geometry Computational topology Applied mathematics Applications of computer graphics include Special effect Special effects Visual effects Video game Video games Digital art History One of the first displays of computer animation ... and journals where the most significant results in computer graphics are published. Among them ... An extensive history of computer graphics can be found at http accad.osu.edu waynec history lessons.html this page . ref Subfields in computer graphics A broad classification of major subfields in computer ... geometric quantities for the discrete surfaces used in computer graphics. ref name columbia ddg ... with light . See Rendering computer graphics for more information. Transport light transport theory ... in computer graphics multicol Jim Blinn Jack E. Bresenham Loren Carpenter Edwin Catmull Robert L. Cook Paul Debevec Ronald Fedkiw Ron Fedkiw James D. Foley multicol break David Forsyth computer ... Williams multicol end See also multicol 3D computer graphics Cloth modeling Computer facial animation ... reflist Further reading James D. Foley Foley et al . Computer Graphics Principles and Practice . Shirley ... more details
std string tt class is a standard representation for a Stringcomputersciencestring of text. This class alleviates many of the problems introduced by C string C style strings by putting the onus of memory ownership on the code string code class rather than on the programmer. The class provides some typical string operations like comparison, concatenation, find and replace, and a function for obtaining substring s. It can be constructed from a C style string, and a C style string can also be obtained from it. Overview of functions code string http en.cppreference.com w cpp string basic string basic stringstring code constructor Constructs the string from variety of sources code string http en.cppreference.com w cpp string basic string basic stringstring code destructor Destructs the string and the contained characters code string http en.cppreference.com w cpp string basic string operator operator code Assigns values to the string code string http en.cppreference.com w cpp string basic string assign assign code Assigns values to the string code string http en.cppreference.com w cpp string basic string get allocator get allocator code Returns the allocator used to allocate memory for the characters Character access code string http en.cppreference.com w cpp string basic string at at code Accesses specified character with bounds checking. code string http en.cppreference.com w cpp string basic string operator at operator nowiki nowiki code Accesses specified character code string http en.cppreference.com w cpp string basic string front front code Accesses the first character code string http en.cppreference.com w cpp string basic string back back code Accesses the last character code string http en.cppreference.com w cpp string basic string data data code Accesses the underlying array Iterators code string http en.cppreference.com w cpp string basic string begin ... dmy dates date January 2012 Category C Category C Standard Library Category Stringcomputerscience ... more details
data structure Array List computing List Tree data structure Tree StringcomputerscienceString Matrix computerscience Databases Database Other Abstraction computerscience Abstraction Big O notation Closure computerscience Closure Compiler Programming paradigms Object oriented programming Object oriented programming Class computerscience Class Inheritance computerscience Inheritance Object computer ...The following outline is provided as an overview of and topical guide to computerscienceComputerscience also called computing science &ndash study of the theoretical foundations of information and computation ... system for computerscience is the ACM Computing Classification System devised by the Association for Computing Machinery . The ACM computerscience body of knowledge is a recommended curriculum for a university level computerscience course. Subfields Mathematical foundations Mathematical ... systems Concurrency computerscience Concurrency The theory and practice of simultaneous computation ... structures and properties Bioinformatics and Computational biology The use of computerscience ... computerscience Computability theory What is calculable with the current models of computers. Proofs ... quantum superposition of bits. History main History of computerscience Vocations Programmer Software ... portal Computerscience Cognitive science External links sisterlinks Computerscience dmoz Computers ComputerScience http www.acm.org education curricula ComputerScience2008.pdf Association for Computing Machinery ACM report on a recommended computerscience curriculum 2008 http www.lecturefox.com computerscience Directory of free university lectures in ComputerScience http liinwww.ira.uka.de bibliography Collection of ComputerScience Bibliographies http se.ethz.ch meyer gallery Photographs ... 2007 2006fall cs1 UCLA ComputerScience 1 Freshman ComputerScience Seminar Section 1 http webcast.berkeley.edu ... Category Outlines Computerscience Category Computerscience Outline Category Computing lists Computer ... more details
Refimprove date November 2009 In computerscience and formal language theory , the empty string or null string ref name Kernighan and Ritchie, C, p. 38 Kernighan and Ritchie, C , p. 38 ref is the unique stringcomputersciencestring of Stringcomputerscience Formal theory length zero . Formal Theory Formally, a string is a finite sequence of symbols such as letters or digits. The empty string is the extreme case where the sequence has length zero, so there are no symbols in the string. There is only one empty string, because two strings are only different if they have different lengths or a different sequence of symbols. In formal treatments, the empty string is denoted with or sometimes or . The empty string should not be confused with the empty language , which is a formal language i.e. a set of strings that contains no strings, not even the empty string. The empty string has several properties math lambda , 0 math . The String 28computer science 29 Formal theory string length is zero. math lambda , s s lambda , s math . The empty string is the identity element of the concatenation ... languages Category Stringcomputerscience Category Zero Formalmethods stub bs Prazni niz de Leeres ... of the empty string produces the empty string. The empty string precedes any other string under ... Memory address memory locations . This means that the same string for example the empty string could be stored in two different places in memory. Note that even a string of length zero can require ... empty string. However, a string comparison function would indicate that all of these empty strings are equal to each other. The empty string is distinct from a null pointer null Reference computerscience reference or null pointer because a null reference does not point to any string at all, not even the empty string. A null reference is likely to cause an error if one tries to perform any operation on it, but an empty string is less likely to do so. The empty string is a legitimate string ... more details
Unreferenced date December 2009 An incompressible Stringcomputersciencestring is one that cannot be Data compression compressed because it lacks sufficient Redundancy information theory repeating sequences . Whether a string is compressible will often depend on the algorithm being used. Some strings are incompressible by any algorithm see Kolmogorov complexity . Example Suppose we have the string 12349999123499991234, and we are using a Data compression compression method that works by putting a special character into the string say followed by a value that points to an entry in a lookup table or dictionary of repeating values. Let s imagine we have an algorithm that examines the string in 4 character chunks. Looking at our string, our algorithm might pick out the values 1234 and 9999 to place into its dictionary. Let s say 1234 is entry 0 and 9999 is entry 1. Now the string can become 0 1 0 1 0 Obviously, this is much shorter, although storing the dictionary itself will cost some space. However, the more repeats there are in the string, the better the compression will be. Our algorithm can do better though, if it can view the string in chunks larger than 4 characters. Then it can put 12349999 and 1234 into the dictionary, giving us 0 0 1 Even shorter. Now let s consider another string 1234999988884321 This string is incompressible by our algorithm. The only repeats that occur are 88 and 99. If we were to store 88 and 99 in our dictionary, we would produce 1234 1 1 0 04321 Unfortunately this is just as long as the original string, because our placeholders for items in the dictionary are 2 bytes long, and the items they replace are the same length. Hence, this string is incompressible by our algorithm. DEFAULTSORT Incompressible String Category Lossless compression algorithms Category Stringcomputerscience ... more details
saved book title Computerscience subtitle cover image cover color Computerscience Main article Computerscience Supporting article History of computerscience Category Wikipedia books on computerscienceComputerscience ... more details
No footnotes date July 2010 In computerscience , the string to string correction problem refers to the minimum number of edit operations necessary to change one Stringcomputersciencestring into another. A single edit operation may be changing a single Character computing symbol of the string into another, deleting, or inserting a symbol. The length of the edit sequence provides a measure of the Hamming distance distance between the two strings. Several algorithm s exist to provide an efficient way to determine string distance and specify the minimum number of transformation operations required. Such algorithms are particularly useful for Delta encoding delta creation operations where something is stored as a set of differences relative to a base version. This allows several versions of a single object to be stored much more efficiently than storing them separately. This holds true even for single versions of several objects if they do not differ greatly, or anything in between. Notably, such difference algorithms are used in molecular biology to provide some measure of kinship between different kinds of organisms based on the similarities of their macromolecule s such as protein s or DNA . See also Delta encoding Levenshtein distance Edit distance References div class references small cite journal author Robert A. Wagner and Michael J. Fischer title The String to String Correction Problem journal Journal of the ACM volume 21 issue 1 year 1974 pages 168 173 doi 10.1145 321796.321811 cite journal author Walter F. Tichy title The string to string correction problem with block moves journal ACM Transactions on Computer Systems volume 2 issue 4 year 1984 pages 309 321 doi 10.1145 357401.357404 div Category Problems on strings Category String similarity measures ... more details
In computerscience and mathematical logic , an alphabet is a non empty set of symbol s or letters , e.g. characters or digits. ref Citation last1 Ebbinghaus first1 H. D. last2 Flum first2 J. last3 Thomas first3 W. doi title Mathematical Logic url http www.springer.com mathematics book 978 0 387 94258 2 publisher Springer Science Business Media Springer location New York City New York edition 2nd isbn 0 387 94258 0 year 1994 defined at beginning of Part A, Section I ref For example a common alphabet is 0,1 , the binary alphabet . A finite Stringcomputersciencestring is a finite sequence of letters from an alphabet for instance a binary string is a string drawn from the alphabet 0,1 . An infinite Infinite sequence Infinite sequences in theoretical computerscience sequence of letters may be constructed from elements of an alphabet as well. Given an alphabet math Sigma math , we write math Sigma math to denote the set of all finite strings over the alphabet math Sigma math . Here, the math math denotes the Kleene star operator, so math Sigma math is also called the Kleene closure of math Sigma math . We write math Sigma infty math or occasionally, math Sigma N math or math Sigma omega math to denote the set of all infinite sequences over the alphabet math Sigma math . For example, if we use the binary alphabet 0,1 , the strings , 0, 1, 00, 01, 10, 11, 000, etc. would all be in the Kleene closure of the alphabet where represents the empty string Alphabets are important in the use of formal languages , Automata theory automata and semiautomaton semiautomata . In most cases, for defining instances of automata, such as deterministic finite automaton deterministic finite automata DFAs , it is required to specify an alphabet from which the input strings for the automaton are built ..., Reading Massachusetts, 1979. ISBN 0 201 029880 X. DEFAULTSORT Alphabet ComputerScience Category ... ru simple Alphabet computerscience sk Abeceda te ria automatov sh Abeceda ... more details
Unreferenced date December 2011 In computerscience , string generation is the process of creating a set of Stringcomputerscience strings from a collection of rules. This is an opposite process to that of parsing , which recognises a string based on some collection of rules. Applications of string generation include test data generation, Captchas and random essay generation. Generation methods Methods for generating strings include While a deterministic finite automaton is often used to recognize strings it can easily be changed to generate strings. Unsolved problems Expand section date December 2011 Unsolved problems in string generation include Note It is an undecidable problem to decide whether a given string can be generated by a given Van Wijngaarden grammar W grammar . Doesn t this mean parsing as opposed to string genreation is undeciadable? See also Pretty printing &ndash another process often considered the dual of parsing. Citation needed date February 2012 External links http regldg.com Generate strings matching a regular expression http search.cpan.org dcoppit yagg 1.4001 yagg Generate strings from a yacc grammar http compilers.iecc.com comparch article 91 04 069 comp.compilers discussion http www.elsewhere.org pomo random essay random essay http embed.cs.utah.edu csmith Generate random C programs Category Algorithms on strings Category Parsing Comp sci stub ... more details
oneref date February 2012 In computerscience, string interning is a method of storing only one copy of each distinct Stringcomputersciencestring value, which must be Immutable object immutable . Interning strings makes some string processing tasks more time or space efficient at the cost of requiring more time when the string is created or interned. The distinct values are stored in a string intern pool . The single copy of each string is called its intern and is typically looked up by a method of the string class, for example Javadoc SE java lang String intern in Java. All compile time constant strings in Java are automatically interned using this method. ref http java.sun.com docs books jls third edition html expressions.html 5313 ref String interning is supported by some modern object oriented programming language s, including Python programming language Python , Ruby programming language Ruby with its symbols , Java programming language Java and List of CLI languages .NET languages ... Visual J String class http msdn2.microsoft.com en us library system.string.intern.aspx .NET String Class Category Software optimization Category Stringcomputerscience Interning pl Internowanie ... with no memory reference at all. String interning also reduces memory usage if there are many instances of the same string value for instance, it is read from a computer network network or from Computer ... used as a string intern pool was called an oblist when it was implemented as a linked list or an obarray ... strings interning a given string returns an existing symbol or creates a new one, whose name is that string ... string with a not necessarily interned string, which could lead to intermittent failures depending on usage patterns. Motivation String interning speeds up string comparisons, which are sometimes a performance ... that rely heavily on hash tables with string keys. Without interning, checking that two different strings ... of Computer data storage Primary storage memory , which take time and the reads fills up the processor ... more details
ACSL , or the American ComputerScience League , is an international computerscience competition among more than 200 school s. Each round consists of two parts a written section and a programming section. Written topics tested include what does this program do? , digital electronics , Boolean algebra logic Boolean algebra , computer numbering formats computer numbering systems , Recursion computerscience recursive function s, data structures primarily dealing with Heap data structure heaps , binary search tree s, stack data structure stacks , and Queue data structure queues , Lisp programming language lisp programming , regular expressions and Finite state machine Finite State Automata , bit string flicking, graph theory , assembly language assembly programming and prefix notation prefix postfix notation postfix infix notation infix notation. Divisions There are four divisions in ACSL Classroom, Junior, Intermediate, and Senior. Junior is recommended for middle school students no students above the ninth grade may compete in it . Intermediate and Senior divisions are for secondary school students, Intermediate being easier and Senior being more difficult. At the All Star final competition, the Junior teams consist of 5 members each while the Senior and Intermediate teams can consist of 3 or 5 members. Each team competes against other same sized teams in its division. Preliminary Competition The preliminary competition, in which individual students compete to get their school team qualified for the All Star competition, consists of four rounds. These rounds consist of a programming ... ComputerScience League http www.acsl.org ACSL web site including past winners http www.scribd.com doc 15606670 American ComputerScience League ACSL Rules and Handbook Handbook and Category Descriptions Category Computerscience competitions ro American ComputerScience League ... computer language to perform a given task. In the written part, students have a total of 30 minutes ... more details
in that it is Synchronization computerscience unsynchronized . When only a single Thread computerscience thread at a time will access the object, using a code StringBuilder code processes more efficiently ...In object oriented programming , a String Buffer is an alternative to a String. It has the ability to be altered through adding or appending, whereas a String is normally fixed or Immutable object immutable . In Java Theory Java Sun Java s standard way to handle text is to use its code Javadoc SE java lang String code Class computerscience class . Any given code String code in Java is an immutable object , which means its State computerscience state cannot be changed. A code String code has an Array data type array of Character computing characters . Whenever a code String code must be manipulated, any changes require the creation of a new code String code which, turn, involves the creation ... code String code s value or intermediate code String code s used for the manipulation are not kept. Java provides an alternate class for string manipulation, called a code http java.sun.com j2se 1.5.0 docs api java lang StringBuffer.html StringBuffer code . A code StringBuffer code , like a code String ... array of characters is not necessarily completely filled as oppose to a String, whose array is always ... an expression like String newString aString anInt aChar aDouble like this String newString new StringBuffer ... is more analysis of algorithms efficient than a String in string handling. However, this is not necessarily ... String would be required, although this is unlikely and the programmer can provide length hints to prevent ... Ruby , the standard string class is already mutable, with the ability to change the contents and append strings, etc., so a separate mutable string class is unnecessary. In Objective C Cocoa API ... api java lang String.html String code . http www.java2s.com Code JavaAPI java.lang StringBuffer.htm ... objects with respect to object oriented design Category Java programming language Category String ... more details
The term Theoretical ComputerScience may refer to The field of theoretical computerscience . Theoretical ComputerScience journal , a journal covering this field. disambig ... more details
In mathematics and computerscience , a string metric also known as a string similarity metric or string distance function is a metric mathematics metric that measure similarity or dissimilarity distance between two stringcomputerscience text strings for approximate string matching or comparison and in fuzzy string searching . For example the strings Sam and Samuel can be considered to be similar. A string metric provides a number indicating an algorithm specific indication of similarity. The most widely known string metric is a rudimentary one called the Levenshtein distance Levenshtein Distance also known as Edit Distance . It operates between two input strings, returning a score equivalent to the number of substitutions and deletions needed in order to transform one input string into another. Simplistic string metrics such as Levenshtein distance have expanded to include phonetic, token parser token , grammatical and character based methods of statistical comparisons. A widespread example of a string metric is DNA sequence analysis and RNA analysis, which are performed by optimised string metrics to identify matching sequences. String metrics are used heavily in information integration and are currently used in areas including fraud detection , fingerprint analysis , plagiarism detection , ontology merging , DNA analysis , RNA analysis, image analysis , evidence based machine learning, database data deduplication , data mining , Web interfaces, e.g. Ajax programming Ajax style suggestions as you type, data integration , and semantic knowledge integration . List of string metrics This can be a separate article, someday. Hamming distance Levenshtein distance and Damerau Levenshtein distance Needleman Wunsch algorithm Needleman Wunsch distance or Sellers algorithm Smith ... matches Lee distance See also approximate string matching String matching SimMetrics an implementation ... http www.dcs.shef.ac.uk sam stringmetrics.html ukkonen DEFAULTSORT String Metric Category String ... more details
In computerscience , in the area of formal language theory , frequent use is made of a variety of string functions however, the notation used is different from that used on computer programming , and some ... of a string is the set of all prefix computerscience prefixes to a string, with respect to a given ... Formal languages Category Relational algebra Category Stringcomputerscience Operations zh ... defines some of these basic terms. Alphabet of a string The alphabet of a string is a list of all of the letters that occur in a particular string. If s is a string, its alphabet computerscience alphabet is denoted by math operatorname Alph s math String substitution Let L be a language computerscience language , and let math Sigma math be its alphabet. A string substitution or simply a substitution ... to strings as math f varepsilon varepsilon math for the empty string math varepsilon math , and math f sa f s f a math for string math s in L math . String substitution may be extended to the entire language as math f L bigcup s in L f s math An example of string substitution occurs in regular language s, which are closed under string substitution. That is, if the letters of a regular language ... is the conversion of an EBCDIC encoded string to ASCII . String homomorphism A string homomorphism often referred to simply as a homomorphism in formal language theory is a string substitution such that each letter is replaced by a single string. That is, math f a s math , where s is a string, for each letter a . String homomorphisms are homomorphism s, preserving the binary operation of string concatenation ... homomorphic image of a string s is defined as math f 1 s w vert f w s math while the inverse ... 1 f L math for any language L . A string homomorphism is said to be math epsilon math free or e free ... cipher s are examples of math epsilon math free string homomorphisms. String projection If s is a string, and math Sigma math is an alphabet, the string projection of s is the string that results ... more details
nofootnotes date September 2010 In computerscience , a Predicate mathematical logic predicate is called an invariant to a sequence of Operation mathematics operations provided that if the predicate is true before starting the sequence, then it is true at the end of the sequence. Use Although computer program s are typically specified in terms of what they change, it s equally important to know or specify the invariants of a program. This is especially useful when reasoning about the program. The theory of optimizing compiler s, the methodology of design by contract , and formal methods for determining program correctness , all pay close attention to invariant s in computer program s. Programmers often make use of Assertion computing assertions in their code to make invariants explicit. Some object oriented programming language s have a special syntax for specifying class invariant s. Example The MU puzzle is a good example of a logical problem where determining an invariant is useful. The puzzle is as follows If a string ends with an I, a U may be appended x I x IU Any string after an M may be completely duplicated M x M xx Any three consecutive I s III may be replaced with a single U x III y x U y Any two consecutive U s may be removed x UU y xy Is it possible to convert MI into MU ..., the only way to get rid of any I s is to have three consecutive I s in the string. This makes the following invariant interesting to consider The number of I s in the string is not a multiple of 3 . This is an invariant ... t be afterwards either. Given that there is a single I in the starting string MI, and one is not a multiple ... basis for computer programming . Communications of the ACM , 12 10 576 585, October 1969. doi 10.1145 ... index.html Applet Visual Invariants in Sorting Algorithms http www.amcgowan.ca blog computerscience how to handle class constructors that fail How to handle class constructors with invariants that fail Category Formal methods terminology Category Computer programming cs Invariant informatika ... more details
A production or production rule in computerscience is a rewrite rule specifying a symbol substitution that can be recursively performed to generate new symbol sequences. A finite set of productions math P math is the main component in the specification of a formal grammar specifically a generative grammar . The other components are a finite set math N math of nonterminal symbol s, a finite set known as an alphabet math Sigma math of terminal symbol s that is Disjoint sets disjoint from math N math and a distinguished symbol math S in N math that is the start symbol. In an unrestricted grammar , a production is of the form math u to v math where math u math and math v math are arbitrary strings of terminals and nonterminals however math u math may not be the empty string. If math v math is the empty string, this is denoted by the symbol math epsilon math , or math lambda math rather than leave the right hand side blank . So productions are of the form math N cup Sigma N N cup Sigma to N cup Sigma math Where math math is the Kleene plus operator, math math is the Kleene star operator, and math cup math denotes union set theory set union . The other types of formal grammar in the Chomsky hierarchy impose additional restrictions on what constitutes a production. Notably in a context ... are of the form math N to N cup Sigma math Grammar generation To generate a string in the language, one begins with a string consisting of only a single start symbol , and then successively applies the rules any number of times, in any order to rewrite this string. This stops when we obtain a string ... string in the language. If there are multiple different ways of generating this single string ... and obtain the string math aSb math . If we choose rule 1 again, we replace math S math with math aSb math and obtain the string math aaSbb math . This process is repeated until we only have symbols from ... with math ba math and obtain the string math aababb math , and are done. We can write this series of choices ... more details
that unifies the computerscience definition of these terms with the definition used ... is also implicitly invoked by method overriding programming overriding method computerscience methods in subclass computerscience subclass es the new method can be used where the old method was invoked ... a more general class polymorphism computerscience polymorphism , leading to the possibility of compiler ... Programming Language, Second Edition pages 8 10 ref See also Polymorphism computerscience Inheritance computerscience References references External links http blogs.msdn.com ericlippert archive ... in C DEFAULTSORT Covariance And Contravariance ComputerScience Category Object oriented programming Category Type theory Category Polymorphism computerscience ar ... is usually covariant on the base type since String Object then ArrayOf String ArrayOf Object . Note ... are permitted, then the insert operator is covariant e.g. one can insert a String into an ArrayOf Object and the remove operator is contravariant e.g. one can remove an Object from an ArrayOf String . Since ... to lack of static type safety for instance, in C code string code is a subtype of code object code , and in Java Javadoc SE java lang String code code is a subtype of Javadoc SE java lang Object ... element array of System.String string a new string 1 b is an array of System.Object object b a Assign ... in Java, too source lang java a is a single element array of StringString a new String 1 b is an array ... of Object, but since it really is an array of String, we will get a java.lang.ArrayStoreException. ... ref source lang csharp object str string source Ever since C 1.0, arrays where the element type ... and contravariance in c part two array covariance.aspx ref source lang csharp object strings new string ... arrays, generic classes are neither covariant nor contravariant. For example, neither code List String ... List of String List String a new ArrayList String a.add foo b is a List of Object List Object b a This is a compile ... more details
An expression in a programming language is a combination of explicit value computerscience value s, Constant programming constants , variable programming variable s, operator programming operator s, and function programming function s that are interpreted according to the particular Order of operations rules of precedence and of association for a particular programming language, which computes and then produces returns , in a state computerscience stateful environment another value. This process, like for mathematical expression s, is called evaluation. The value can be of various Data type type s, such as numerical, string, and logical. For example, 2 3 is an arithmetic and programming expression which evaluates to 5. A variable is an expression because it denotes a value in memory, so y 6 is an expression. An example of a relational expression is 4 4, which evaluates to false. ref https developer.mozilla.org en Core JavaScript 1.5 Guide Expressions Javascript expressions, Mozilla Accessed July 6, 2009 ref ref https www.cs.drexel.edu rweaver COURSES ISTC 2 TOPICS expr.html Programming in C Accessed July 6, 2009 ref In C programming language C and most C derived languages, a call to a function with a Void type void return type is a valid expression, of type void. ref http www.open std.org JTC1 SC22 WG14 www docs n1256.pdf ISO IEC 9899 1999 section 6.3.2.2, accessed August 31, 2009 ref Values of type void cannot be used, so the value of such an expression is always thrown away. A function, and hence an expression containing a function, may have Side effect computerscience side effect s. An expression with side effects does not normally have the property of referential transparency computerscience referential transparency . In many languages e.g. C , statements may be ended with a semicolon code code to turn the expression into an expression Statement programming statement . This asks the implementation to evaluate the expression for its side effects only, and disregard ... more details
Information and ComputerScience ICS or Computer and Information Science CIS plural forms, i.e. Sciences , may also be used is a field that emphasizes both computing and Informatics academic field informatics , upholding the strong association between the fields of information science s and computerscience s and treating computers as a tool rather than a field. Computing Paradigm Due to the distinction between computers and computing, some research groups wholly replace computer with computing or datalogy , creating names such as Computing and Information Science . Languages may also entirely omit the association for example, computerscience in French is known as fr Informatique informatique . Education Universities may confer degrees of ICS and CIS, not to be confused with a more specific Bachelor of ComputerScience or respective graduate ComputerScience degrees. Comp sci stub Category Information science ... more details
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