Wildcard Characters
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Wildcard Characters
In software, a wildcard character is a kind of placeholder represented by a single character, such as an asterisk (), which can be interpreted as a number of literal characters or an empty string. It is often used in file searches so the full name need not be typed. Telecommunication In telecommunications, a wildcard is a character that may be substituted for any of a defined subset of all possible characters. * In high-frequency (HF) radio automatic link establishment, the wildcard character may be substituted for any one of the 36 upper-case alphanumeric characters. * Whether the wildcard character represents a single character or a string of characters must be specified. Computing In computer (software) technology, a wildcard is a symbol used to replace or represent one or more characters. Algorithms for matching wildcards have been developed in a number of recursive and non-recursive varieties. File and directory patterns When specifying file names (or paths) in CP/M, DO ...
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Wildcard
Wild card most commonly refers to: * Wild card (cards), a playing card that substitutes for any other card in card games * Wild card (sports), a tournament or playoff place awarded to an individual or team that has not qualified through normal play Wild card, wild cards or Wildcard may also refer to: Computing * Wildcard character, a character that substitutes for any other character or character range in regular expressions and globbing * Wildcard DNS record, a record in a DNS zone file that will match all requests for non-existent domain names * Wildcard mask, a netmask that swaps 1 to 0 and 0 to 1 compared to the normal netmask * Wildcard certificate, a public key certificate with which you can secure multiple subdomains * Wildcard (Java), a special actual type parameter for generic instantiations in the Java programming language * Studio Wildcard, an American video game developer best known for ''Ark: Survival Evolved'' Books * ''Wild Cards'', an anthology series of scie ...
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Question Mark
The question mark (also known as interrogation point, query, or eroteme in journalism) is a punctuation mark that indicates an interrogative clause or phrase in many languages. History In the fifth century, Syriac Bible manuscripts used question markers, according to a 2011 theory by manuscript specialist Chip Coakley: he believes the ''zagwa elaya'' ("upper pair"), a vertical double dot over a word at the start of a sentence, indicates that the sentence is a question. From around 783, in ''Godescalc Evangelistary'', a mark described as "a lightning flash, striking from right to left" is attested. This mark is later called a . According to some paleographers, it may have indicated intonation, perhaps associated with early musical notation like neumes. Another theory, is that the "lightning flash" was originally a tilde or titlo, as in , one of many wavy or more or less slanted marks used in medieval texts for denoting things such as abbreviations, which would later become ...
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Kleene Star
In mathematical logic and computer science, the Kleene star (or Kleene operator or Kleene closure) is a unary operation, either on sets of strings or on sets of symbols or characters. In mathematics, it is more commonly known as the free monoid construction. The application of the Kleene star to a set V is written as ''V^*''. It is widely used for regular expressions, which is the context in which it was introduced by Stephen Kleene to characterize certain automata, where it means "zero or more repetitions". # If V is a set of strings, then ''V^*'' is defined as the smallest superset of V that contains the empty string \varepsilon and is closed under the string concatenation operation. # If V is a set of symbols or characters, then ''V^*'' is the set of all strings over symbols in V, including the empty string \varepsilon. The set ''V^*'' can also be described as the set containing the empty string and all finite-length strings that can be generated by concatenating arbitrary e ...
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Full Stop
The full stop (Commonwealth English), period (North American English), or full point , is a punctuation mark. It is used for several purposes, most often to mark the end of a declarative sentence (as distinguished from a question or exclamation). This sentence-ending use, alone, defines the strictest sense of ''full stop''. Although ''full stop'' technically applies only when the mark is used to end a sentence, the distinction – drawn since at least 1897 – is not maintained by all modern style guides and dictionaries. The mark is also used, singly, to indicate omitted characters or, in a series, as an ellipsis (), to indicate omitted words. It may be placed after an initial letter used to stand for a name or after each individual letter in an initialism or acronym (e.g., "U.S.A."). However, the use of full stops after letters in an initialism or acronym is declining, and many of these without punctuation have become accepted norms (e.g., "UK" and "NATO"). This trend has pro ...
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Regular Expression
A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. Regular expression techniques are developed in theoretical computer science and formal language theory. The concept of regular expressions began in the 1950s, when the American mathematician Stephen Cole Kleene formalized the concept of a regular language. They came into common use with Unix text-processing utilities. Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax. Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Most gener ...
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Number Sign
The symbol is known variously in English-speaking regions as the number sign, hash, or pound sign. The symbol has historically been used for a wide range of purposes including the designation of an ordinal number and as a Typographic ligature, ligatured abbreviation for Pound (mass), pounds avoirdupois – having been derived from the now-rare . Since 2007, widespread usage of the symbol to introduce metadata tags on social media platforms has led to such tags being known as "hashtags", and from that, the symbol itself is sometimes called a hashtag. The symbol is distinguished from similar symbols by its combination of level horizontal strokes and right-tilting vertical strokes. History It is believed that the symbol traces its origins to the symbol , an abbreviation of the Roman term ''Roman pound, libra pondo'', which translates as "pound weight". This abbreviation was printed with a dedicated Ligature (writing), ligature type element, with a horizontal line across, so t ...
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Microsoft Access
Microsoft Access is a database management system (DBMS) from Microsoft that combines the relational Access Database Engine (ACE) with a graphical user interface and software-development tools (not to be confused with the old Microsoft Access which was a telecommunication program that provided terminal emulation and interfaces for ease of use in accessing online services such as Dow Jones, Compuserve and electronic mailbox in the 1980s). It is a member of the Microsoft 365 suite of applications, included in the Professional and higher editions or sold separately. Microsoft Access stores data in its own format based on the Access Database Engine (formerly Jet Database Engine). It can also import or link directly to data stored in other applications and databases. Software developers, data architects and power users can use Microsoft Access to develop application software. Like other Microsoft Office applications, Access is supported by Visual Basic for Applications (VBA), an obj ...
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Transact-SQL
Transact-SQL (T-SQL) is Microsoft's and Sybase's proprietary extension to the SQL (Structured Query Language) used to interact with relational databases. T-SQL expands on the SQL standard to include procedural programming, local variables, various support functions for string processing, date processing, mathematics, etc. and changes to the DELETE and UPDATE statements. Transact-SQL is central to using Microsoft SQL Server. All applications that communicate with an instance of SQL Server do so by sending Transact-SQL statements to the server, regardless of the user interface of the application. Stored procedures in SQL Server are executable server-side routines. The advantage of stored procedures is the ability to pass parameters. Variables Transact-SQL provides the following statements to declare and set local variables: DECLARE, SET and SELECT. DECLARE @var1 NVARCHAR(30); SET @var1 = 'somya som'; SELECT @var1 = Name FROM Sales.Store WHERE CustomerID = 100; Flow contr ...
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Underscore
An underscore, ; also called an underline, low line, or low dash; is a line drawn under a segment of text. In proofreading, underscoring is a convention that says "set this text in italic type", traditionally used on Manuscript (publishing), manuscript or Manuscript#Modern variations, typescript as an List of proofreader's marks, instruction to the printer. Its use to add emphasis in modern documents is a deprecated practice. The underscore character, , originally appeared on the typewriter and was primarily used to emphasise words as in #Manuscripts, the proofreader's convention. To produce an underscored word, the word was typed, the typewriter carriage was moved back to the beginning of the word, and the word was overstrike, overtyped with the underscore character. In modern usage, underscoring is achieved by Markup language, markup or with combining characters. The original free-standing underscore character continues in use to create visual spacing within a sequence of char ...
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Percent
In mathematics, a percentage (from la, per centum, "by a hundred") is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also used. A percentage is a dimensionless number (pure number); it has no unit of measurement. Examples For example, 45% (read as "forty-five per cent") is equal to the fraction , the ratio 45:55 (or 45:100 when comparing to the total rather than the other portion), or 0.45. Percentages are often used to express a proportionate part of a total. (Similarly, one can also express a number as a fraction of 1,000, using the term "per mille" or the symbol "".) Example 1 If 50% of the total number of students in the class are male, that means that 50 out of every 100 students are male. If there are 500 students, then 250 of them are male. Example 2 An increase of $0.15 on a price of $2.50 is an increase by a fraction of = 0.06. Expressed as a pe ...
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Like (SQL)
A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria. The criteria are expressed in the form of predicates. WHERE clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned by a query. In brief SQL WHERE clause is used to extract only those results from a SQL statement, such as: SELECT, INSERT, UPDATE, or DELETE statement. Overview WHERE is an SQL reserved word. The WHERE clause is used in conjunction with SQL DML statements, and takes the following general form: SQL-DML-Statement FROM table_name WHERE predicate all rows for which the predicate in the WHERE clause is True are affected (or returned) by the SQL DML statement or query. Rows for which the predicate evaluates to False or Unknown (NULL) are unaffected by the DML statement or query. The following query returns only those rows from table ''myt ...
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Glob (programming)
In computer programming, glob () patterns specify sets of filenames with wildcard characters. For example, the Unix Bash shell command mv *.txt textfiles/ moves (mv) all files with names ending in .txt from the current directory to the directory textfiles. Here, * is a wildcard standing for "any string of characters except /" and *.txt is a glob pattern. The other common wildcard is the question mark (?), which stands for one character. For example, mv ?.txt shorttextfiles/ will move all files named with a single character followed by .txt from the current directory to directory shorttextfiles, while ??.txt would match all files whose name consists of 2 characters followed by .txt. In addition to matching filenames, globs are also used widely for matching arbitrary strings ( wildcard matching). In this capacity a common interface is fnmatch. Origin The glob command, short for ''global'', originates in the earliest versions of Bell Labs' Unix. The command interpreters of the ear ...
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