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Literal String
A string literal or anonymous string is a string value in the source code of a computer program. Modern programming languages commonly use a quoted sequence of characters, formally " bracketed delimiters", as in x = "foo", where "foo" is a string literal with value foo. Methods such as escape sequences can be used to avoid the problem of delimiter collision (issues with brackets) and allow the delimiters to be embedded in a string. There are many alternate notations for specifying string literals especially in complicated cases. The exact notation depends on the programming language in question. Nevertheless, there are general guidelines that most modern programming languages follow. Syntax Bracketed delimiters Most modern programming languages use bracket delimiters (also balanced delimiters) to specify string literals. Double quotations are the most common quoting delimiters used: "Hi There!" An empty string is literally written by a pair of quotes with no character ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Literal (computer Programming)
In computer science, a literal is a notation for representing a fixed value in source code. Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, and usually for booleans and characters; some also have notations for elements of enumerated types and compound values such as arrays, records, and objects. An anonymous function is a literal for the function type. In contrast to literals, variables or constants are symbols that can take on one of a class of fixed values, the constant being constrained not to change. Literals are often used to initialize variables; for example, in the following, 1 is an integer literal and the three letter string in "cat" is a string literal: int a = 1; string s = "cat"; In lexical analysis, literals of a given type are generally a token type, with a grammar rule, like "a string of digits" for an integer literal. Some literals are specific keywords, like true for the boolean lit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apostrophe
The apostrophe ( or ) is a punctuation mark, and sometimes a diacritical mark, in languages that use the Latin alphabet and some other alphabets. In English, the apostrophe is used for two basic purposes: * The marking of the omission of one or more letters, e.g. the contraction of "do not" to "don't". * The marking of possessive case of nouns (as in "the eagle's feathers", "in one month's time", "at your parents' ome). The word "apostrophe" comes ultimately from Greek (, ' he accent ofturning away or elision'), through Latin and French. For use in computer systems, Unicode has code points for three different forms of apostrophe. Usage in English Historical development The apostrophe was first used by Pietro Bembo in his edition of '' De Aetna'' (1496). It was introduced into English in the 16th century in imitation of French practice. French practice Introduced by Geoffroy Tory (1529), the apostrophe was used in place of a vowel letter to indicate elision (as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metacharacter
A metacharacter is a character that has a special meaning to a computer program, such as a shell interpreter or a regular expression (regex) engine. In POSIX extended regular expressions, there are 14 metacharacters that must be ''escaped'' (preceded by a backslash (\)) in order to drop their special meaning and be treated literally inside an expression: opening and closing square brackets ( _and_.html" ;"title="/code> and ">/code> and /code>); backslash (\); caret (^); dollar sign ($); period/full stop/dot (.); vertical bar/pipe symbol (, ); question mark (?); asterisk (*); plus and minus signs (+ and -); opening and closing curly brackets/braces (); and opening and closing parentheses (( and )). For example, to match the arithmetic expression (1+1)*3=6 with a regex, the correct regex is \(1\+1\)\*3=6; otherwise, the parentheses, plus sign, and asterisk will have special meanings. Other examples Some other characters may have special meaning in some environments. * In some Unix ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delimiter Collision
A delimiter is a sequence of one or more characters for specifying the boundary between separate, independent regions in plain text, mathematical expressions or other data streams. An example of a delimiter is the comma character, which acts as a ''field delimiter'' in a sequence of comma-separated values. Another example of a delimiter is the time gap used to separate letters and words in the transmission of Morse code. In mathematics, delimiters are often used to specify the scope of an operation, and can occur both as isolated symbols (e.g., colon in "1 : 4") and as a pair of opposing-looking symbols (e.g., angled brackets in \langle a, b \rangle). Delimiters represent one of various means of specifying boundaries in a data stream. Declarative notation, for example, is an alternate method that uses a length field at the start of a data stream to specify the number of characters that the data stream contains. describing the method in Hollerith notation under the Fortran p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Overhead
In computer science, overhead is any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to perform a specific task. It is a special case of engineering overhead. Overhead can be a deciding factor in software design, with regard to structure, error correction, and feature inclusion. Examples of computing overhead may be found in Object Oriented Programming (OOP), functional programming, data transfer, and data structures. Software design Choice of implementation A programmer/software engineer may have a choice of several algorithms, encodings, data types or data structures, each of which have known characteristics. When choosing among them, their respective overhead should also be considered. Tradeoffs In software engineering, overhead can influence the decision whether or not to include features in new products, or indeed whether to fix bugs. A feature that has a high overhead may not be included – or needs a big ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hollerith Constant
Hollerith constants, named in honor of Herman Hollerith, were used in early FORTRAN programs to allow manipulation of character data. Early FORTRAN had no CHARACTER data type, only numeric types. In order to perform character manipulation, characters needed to be placed into numeric variables using Hollerith constants. For example, the constant 3HABC specified a three-character string "ABC", identified by the initial integer representing the string length 3 and the specified Hollerith character H, followed by the string data ABC. These constants were '' typeless'', so that there were no type conversion issues. If the constant specified fewer characters than was possible to hold in a data item, the characters were then stored in the item ''left-justified'' and ''blank-filled''. Mechanics By the FORTRAN 66 Standard, Hollerith syntax was allowed in the following uses: * As constants in DATA statements * As constant actual arguments in subroutine CALL statements * As edit descrip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whitespace Character
In computer programming, whitespace is any character or series of characters that represent horizontal or vertical space in typography. When rendered, a whitespace character does not correspond to a visible mark, but typically does occupy an area on a page. For example, the common whitespace symbol (also ASCII 32) represents a blank space punctuation character in text, used as a word divider in Western scripts. Overview With many keyboard layouts, a whitespace character may be entered by pressing . Horizontal whitespace may also be entered on many keyboards with the key, although the length of the space may vary. Vertical whitespace may be input by typing , which creates a 'newline' code sequence in most programs. On older keyboards, this key may instead be labeled , a holdover from typewriter keyboards' carriage return keys, which generated an electromechanical return to the left stop (Unicode character ) and a move to the next line (). Many early computer games used whitesp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YAML
YAML ( and ) (''see '') is a human-readable data-serialization language. It is commonly used for configuration files and in applications where data is being stored or transmitted. YAML targets many of the same communications applications as Extensible Markup Language (XML) but has a minimal syntax which intentionally differs from Standard Generalized Markup Language (SGML). It uses both Python-style indentation to indicate nesting, and a more compact format that uses for lists and for maps thus JSON files are valid YAML 1.2. Custom data types are allowed, but YAML natively encodes scalars (such as strings, integers, and floats), lists, and associative arrays (also known as maps, dictionaries or hashes). These data types are based on the Perl programming language, though all commonly used high-level programming languages share very similar concepts. The colon-centered syntax, used for expressing key-value pairs, is inspired by electronic mail headers as defined in , and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, engineering, mathematical, technological and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology and software engineering. The term "computing" is also synonymous with counting and calculating. In earlier times, it was used in reference to the action performed by mechanical computing machines, and before that, to human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. Computing is intimately tied to the representation of numbers, though mathematical conc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null
Null may refer to: Science, technology, and mathematics Computing *Null (SQL) (or NULL), a special marker and keyword in SQL indicating that something has no value *Null character, the zero-valued ASCII character, also designated by , often used as a terminator, separator or filler. This symbol has no visual representation *Null pointer or reference (sometimes written NULL, nil, or None), an object pointer (or reference) not currently set to point (or refer) to a valid object Mathematics *Null (mathematics), a zero value in several branches of mathematics Physics *Null (physics), a point in a field where the field quantity is zero *Null (radio), a concept in electromagnetism Arts and media *The Null Corporation, an imprint of the band Nine Inch Nails * ''Null'' (Intronaut EP), 2006 * ''Null'' (Foetus EP), 1995 *Null, an identity of the character Gray Fox in the ''Metal Gear Solid: Portable Ops'' video game *Null, a villain from ''Teenage Mutant Ninja Turtles Adventures'' People ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MediaWiki
MediaWiki is a free and open-source wiki software. It is used on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites define a large part of the requirement set for MediaWiki. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003. MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker. Magnus Manske's announcement of "PHP Wikipedia", wikipedia-l, August 24, 2001 Its development has since then been coordinated by the Wikimedia Foundation. MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of views per second. Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
