Caret
Encyclopedia
Caret usually refers to the spacing symbol
^ in ASCII
(at code point
5Ehex
) and other character sets. In Unicode
, however, the corresponding character is , whereas the Unicode character named caret is actually a similar but lowered symbol: .
A caret can also be called a wedge, up-arrow, hat, control character
, or chevron.
In graphical user interface
terminology, caret sometimes refers to a text insertion point indicator, often a blinking vertical bar. In this context, it may be used interchangeably with the word cursor
.
mark to indicate where a punctuation mark, word, or phrase should be inserted in a document. The term comes from the Latin
caret, "it lacks", from 'carēre', to lack; to be separated from; to be free from. The caret symbol is written below the line of text for a line-level punctuation mark such as a comma
, or above for a higher character such as an apostrophe
; the material to be inserted may be placed inside the caret, in the margin, or above the line.
A raised variant of the character can be found on some typewriters, where it is used to denote a circumflex
in some languages, such as French
and Portuguese
. It is typically a dead key
, which does not cause the carriage to advance and thus allows the following letter to strike the same spot (below the circumflex) on the paper.
In the original 1963 version of the ASCII standard, code point 5Ehex was reserved for an up-arrow . However, the 1965 ECMA-6 standard replaced the up-arrow with a circumflex ( ), which was applicable as a diacritic as well, and two years later, the second revision of ASCII followed suit. As the early mainframe
s and minicomputer
s largely used teleprinter
s as output devices, it was possible to print the circumflex above a letter when needed. With the proliferation of monitor
s, however, this became insufficient, and precomposed character
s, with the diacritic included, were instead introduced into appended character sets, such as Latin-1. The original circumflex character was left for other purposes, and as it did not need to fit above a letter anymore, it was made larger in appearance.
, the caret can signify exponentiation
(3^5 for
), where the usual superscript
is not readily usable (as on some graphing calculator
s). The use of the caret for exponentiation can be traced back to ALGOL 60
, which expressed the exponentiation operator as an upward-pointing arrow, intended to evoke the superscript notation common in mathematics. The caret is also used to indicate a superscript in typesetting.
The caret has many uses in programming language
s. It can signify exponentiation, the bitwise XOR operator, string concatenation, and control character
s in caret notation
, among other uses. In regular expression
s, the caret is used to mark the beginning of a string, or the beginning of a line within that string (depending on the regular expression dialect and specified options); if it begins a character class, it indicates that the inverse of the class is to be matched. Pascal
uses the caret when dereferencing pointers.
The command-line interpreter, cmd.exe
, of Windows family of operating systems uses the caret to escape
reserved characters.
In C++/CLI the only type of pointer is C++ pointer, and the .NET reference types are accessed through a "handle", with the new syntax ClassName^ instead of ClassName*. This new construct is especially helpful when managed and standard C++ code is mixed; it clarifies which objects are under .NET automatic garbage collection and which objects the programmer must remember to explicitly destroy. In development for Apple's Mac OS X and iOS, carets are used to create blocks
, and to denote block types.
In logic
, an enlarged caret called a wedge symbol is used as a propositional operator
to symbolize logical conjunction
, otherwise known as an and (e.g., p
q).
In Italian
, the caret is sometimes used in a similar manner to the ordinal indicator
, most noticeably on tickets from Trenitalia
, the primary operator of trains within Italy, and Rome's
ATAC public transit system. On Trenitalia tickets, the travel class
is often written as 1^ or 2^, meaning first class
or second class respectively. This is due to the lack of the ordinal indicator (-o) used in Italian in the ASCII set.
In music notation, a caret placed above a note indicates marcato
, a special form of emphasis or accent
. In music for string instrument
s, a narrow inverted caret indicates that a note should be performed up-bow.
In music theory
and musicology
, a caret placed above a numeral is used to make reference to a particular scale degree
.
In social network service
s such as Twitter
, a caret placed before a word is used to tag that word as an individual's signature within a group account. This differentiates an individual's contribution from a group-authored contribution.
Symbol
A symbol is something which represents an idea, a physical entity or a process but is distinct from it. The purpose of a symbol is to communicate meaning. For example, a red octagon may be a symbol for "STOP". On a map, a picture of a tent might represent a campsite. Numerals are symbols for...
^ in ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
(at code point
Code point
In character encoding terminology, a code point or code position is any of the numerical values that make up the code space . For example, ASCII comprises 128 code points in the range 0hex to 7Fhex, Extended ASCII comprises 256 code points in the range 0hex to FFhex, and Unicode comprises 1,114,112...
5Ehex
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
) and other character sets. In Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
, however, the corresponding character is , whereas the Unicode character named caret is actually a similar but lowered symbol: .
A caret can also be called a wedge, up-arrow, hat, control character
Control character
In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
, or chevron.
In graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
terminology, caret sometimes refers to a text insertion point indicator, often a blinking vertical bar. In this context, it may be used interchangeably with the word cursor
Cursor (computers)
In computing, a cursor is an indicator used to show the position on a computer monitor or other display device that will respond to input from a text input or pointing device. The flashing text cursor may be referred to as a caret in some cases...
.
Origins
As the variation in naming shows, the origins of the character are twofold. The caret was originally used, and continues to be, in handwritten form as a proofreadingProofreading
Proofreading is the reading of a galley proof or computer monitor to detect and correct production-errors of text or art. Proofreaders are expected to be consistently accurate by default because they occupy the last stage of typographic production before publication.-Traditional method:A proof is...
mark to indicate where a punctuation mark, word, or phrase should be inserted in a document. The term comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
caret, "it lacks", from 'carēre', to lack; to be separated from; to be free from. The caret symbol is written below the line of text for a line-level punctuation mark such as a comma
Comma
A comma is a type of punctuation mark . The word comes from the Greek komma , which means something cut off or a short clause.Comma may also refer to:* Comma , a type of interval in music theory...
, or above for a higher character such as an apostrophe
Apostrophe
The apostrophe is a punctuation mark, and sometimes a diacritic mark, in languages that use the Latin alphabet or certain other alphabets...
; the material to be inserted may be placed inside the caret, in the margin, or above the line.
A raised variant of the character can be found on some typewriters, where it is used to denote a circumflex
Circumflex
The circumflex is a diacritic used in the written forms of many languages, and is also commonly used in various romanization and transcription schemes. It received its English name from Latin circumflexus —a translation of the Greek περισπωμένη...
in some languages, such as French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
and Portuguese
Portuguese language
Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...
. It is typically a dead key
Dead key
A dead key is a special kind of a modifier key on a typewriter or computer keyboard that is typically used to attach a specific diacritic to a base letter. The dead key does not generate a character by itself but modifies the character generated by the key struck immediately after...
, which does not cause the carriage to advance and thus allows the following letter to strike the same spot (below the circumflex) on the paper.
In the original 1963 version of the ASCII standard, code point 5Ehex was reserved for an up-arrow . However, the 1965 ECMA-6 standard replaced the up-arrow with a circumflex ( ), which was applicable as a diacritic as well, and two years later, the second revision of ASCII followed suit. As the early mainframe
Mainframe computer
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...
s and minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s largely used teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
s as output devices, it was possible to print the circumflex above a letter when needed. With the proliferation of monitor
Monochrome monitor
A monochrome monitor is a type of CRT computer display which was very common in the early days of computing, from the 1960s through the 1980s, before color monitors became popular. They are still widely used in applications such as computerized cash register systems...
s, however, this became insufficient, and precomposed character
Precomposed character
A precomposed character is a Unicode entity that can be defined as a combination of two or more other characters. A precomposed character may typically represent a letter with a diacritical mark, such as é...
s, with the diacritic included, were instead introduced into appended character sets, such as Latin-1. The original circumflex character was left for other purposes, and as it did not need to fit above a letter anymore, it was made larger in appearance.
Other uses
In mathematicsMathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
, the caret can signify exponentiation
Exponentiation
Exponentiation is a mathematical operation, written as an, involving two numbers, the base a and the exponent n...
(3^5 for
), where the usual superscriptSubscript and superscript
A subscript or superscript is a number, figure, symbol, or indicator that appears smaller than the normal line of type and is set slightly below or above it – subscripts appear at or below the baseline, while superscripts are above...
is not readily usable (as on some graphing calculator
Graphing calculator
A graphing calculator typically refers to a class of handheld calculators that are capable of plotting graphs, solving simultaneous equations, and performing numerous other tasks with variables...
s). The use of the caret for exponentiation can be traced back to ALGOL 60
ALGOL 60
ALGOL 60 is a member of the ALGOL family of computer programming languages. It gave rise to many other programming languages, including BCPL, B, Pascal, Simula, C, and many others. ALGOL 58 introduced code blocks and the begin and end pairs for delimiting them...
, which expressed the exponentiation operator as an upward-pointing arrow, intended to evoke the superscript notation common in mathematics. The caret is also used to indicate a superscript in typesetting.
The caret has many uses in programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s. It can signify exponentiation, the bitwise XOR operator, string concatenation, and control character
Control character
In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
s in caret notation
Caret notation
Caret notation is a notation for unprintable control characters in ASCII encoding. The notation consists of a caret followed by a capital letter; this digraph stands for the ASCII code that has the numerical value equivalent to the letter's numerical value. For example the EOT character with a...
, among other uses. In regular expression
Regular expression
In computing, a regular expression provides a concise and flexible means for "matching" strings of text, such as particular characters, words, or patterns of characters. Abbreviations for "regular expression" include "regex" and "regexp"...
s, the caret is used to mark the beginning of a string, or the beginning of a line within that string (depending on the regular expression dialect and specified options); if it begins a character class, it indicates that the inverse of the class is to be matched. Pascal
Pascal (programming language)
Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
uses the caret when dereferencing pointers.
The command-line interpreter, cmd.exe
Cmd.exe
Command Prompt is the Microsoft-supplied command-line interpreter on OS/2, Windows CE and on Windows NT-based operating systems...
, of Windows family of operating systems uses the caret to escape
Escape character
In computing and telecommunication, an escape character is a character which invokes an alternative interpretation on subsequent characters in a character sequence. An escape character is a particular case of metacharacters...
reserved characters.
In C++/CLI the only type of pointer is C++ pointer, and the .NET reference types are accessed through a "handle", with the new syntax ClassName^ instead of ClassName*. This new construct is especially helpful when managed and standard C++ code is mixed; it clarifies which objects are under .NET automatic garbage collection and which objects the programmer must remember to explicitly destroy. In development for Apple's Mac OS X and iOS, carets are used to create blocks
Blocks (C language extension)
Blocks are a nonstandard extension added by Apple Inc. to the C, C++, and Objective-C programming languages that uses a lambda expression-like syntax to create closures within these languages...
, and to denote block types.
In logic
Logic
In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
, an enlarged caret called a wedge symbol is used as a propositional operator
Logical connective
In logic, a logical connective is a symbol or word used to connect two or more sentences in a grammatically valid way, such that the compound sentence produced has a truth value dependent on the respective truth values of the original sentences.Each logical connective can be expressed as a...
to symbolize logical conjunction
Logical conjunction
In logic and mathematics, a two-place logical operator and, also known as logical conjunction, results in true if both of its operands are true, otherwise the value of false....
, otherwise known as an and (e.g., p
q).In Italian
Italian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...
, the caret is sometimes used in a similar manner to the ordinal indicator
Ordinal indicator
In written languages, an ordinal indicator is a sign adjacent to a numeral denoting that it is an ordinal number, rather than a cardinal number. The exact sign used varies in different languages.- English :...
, most noticeably on tickets from Trenitalia
Trenitalia
Trenitalia is the primary train operator in Italy. Trenitalia is owned by Ferrovie dello Stato, itself owned by the Italian Government. It was created in 2000 following the EU directive on the deregulation of rail transport.-Passenger transport:...
, the primary operator of trains within Italy, and Rome's
Rome
Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...
ATAC public transit system. On Trenitalia tickets, the travel class
Travel class
A travel class is a quality of accommodation on public transport. The accommodation could be a seat or a cabin for example. Higher travel classes are more comfortable and more expensive.-Airline booking codes:...
is often written as 1^ or 2^, meaning first class
First class travel
First class is the most luxurious class of accommodation on a train, passenger ship, airplane, or other conveyance. It is usually much more expensive than business class and economy class, and offers the best amenities.-Aviation:...
or second class respectively. This is due to the lack of the ordinal indicator (-o) used in Italian in the ASCII set.
In music notation, a caret placed above a note indicates marcato
Marcato
Marcato is a musical instruction indicating a note, chord, or passage is to be played louder or more forcefully than surrounding music. The instruction may involve the word marcato itself written above or below the staff or it may take the form of an accent mark, ^ , an open vertical wedge...
, a special form of emphasis or accent
Accent (music)
In music, an accent is an emphasis placed on a particular note,either as a result of its context or specifically indicated by an accent mark.Accents contribute to the articulation and prosody of a performance of a musical phrase....
. In music for string instrument
String instrument
A string instrument is a musical instrument that produces sound by means of vibrating strings. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones...
s, a narrow inverted caret indicates that a note should be performed up-bow.
In music theory
Music theory
Music theory is the study of how music works. It examines the language and notation of music. It seeks to identify patterns and structures in composers' techniques across or within genres, styles, or historical periods...
and musicology
Musicology
Musicology is the scholarly study of music. The word is used in narrow, broad and intermediate senses. In the narrow sense, musicology is confined to the music history of Western culture...
, a caret placed above a numeral is used to make reference to a particular scale degree
Degree (music)
In music theory, a scale degree or scale step is the name of a particular note of a scale in relation to the tonic...
.
In social network service
Social network service
A social networking service is an online service, platform, or site that focuses on building and reflecting of social networks or social relations among people, who, for example, share interests and/or activities. A social network service consists of a representation of each user , his/her social...
s such as Twitter
Twitter
Twitter is an online social networking and microblogging service that enables its users to send and read text-based posts of up to 140 characters, informally known as "tweets".Twitter was created in March 2006 by Jack Dorsey and launched that July...
, a caret placed before a word is used to tag that word as an individual's signature within a group account. This differentiates an individual's contribution from a group-authored contribution.