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A carriage return, sometimes known as a cartridge return and often shortened to CR, <CR> or return, is a control character or mechanism used to reset a device's position to the beginning of a line of text. It is closely associated with the line feed and newline concepts, although it can be considered separately in its own right.
Originally, the term "carriage return" referred to a mechanism or lever on a typewriter. For machines where the type element was fixed and the paper held in a moving carriage, this lever was on the left attached to the moving carriage, and operated after typing a line of text to cause the carriage to return to the far right so the type element would be aligned to the left side of the paper. The lever would also usually feed the paper to advance to the next line.
Many electric typewriters such as IBM Electric or Underwood Electric made carriage return to be another key on the keyboard instead of a lever. The key was usually labeled "carriage return", "return", or "power return". With typewriters like the Selectric, where the type element moved when typing and the paper was held stationary, the key returned the type element to the far left and the term "carrier return" was sometimes used for this function.
To improve the keyboard for non-English-speakers, the symbol ↵ (U+21B5, HTML entity ↵) was introduced to communicate the combined carriage return and line feed action.
In computing, the carriage return is one of the control characters in ASCII code, Unicode, EBCDIC, and many other codes. It commands a printer, or other output system such as the display of a system console, to move the position of the cursor to the first position on the same line. It was mostly used along with line feed (LF), a move to the next line, so that together they start a new line. Together, this sequence can be referred to as CRLF. [1]
The carriage return and line feed functions were split for practical reasons:
As early as 1901, Baudot code contained separate carriage return and line feed characters.
Many computer programs use the carriage return character, alone or with a line feed, to signal the end of a line of text, but other characters are also used for this function (see newline); others use it only for a paragraph break (a "hard return"). Some standards which introduce their own representations for line and paragraph control (for example HTML) and many programming languages treat carriage return and line feed as whitespace.
In both ASCII and Unicode, the carriage return is assigned code point 13 (or 0D in hexadecimal); it may also be seen as control+M or ^M. In character and string constants in the C programming language and in many other languages (including representations of regular expressions [2] [3] ) influenced by C, \r denotes this character. [4]
ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of technical limitations of computer systems at the time it was invented, ASCII has just 128 code points, of which only 95 are printable characters, which severely limited its scope. Modern computer systems have evolved to use Unicode, which has millions of code points, but the first 128 of these are the same as the ASCII set.
The Baudot code is an early character encoding for telegraphy invented by Émile Baudot in the 1870s. It was the predecessor to the International Telegraph Alphabet No. 2 (ITA2), the most common teleprinter code in use before ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal by asynchronous serial communication. The symbol rate measurement is known as baud, and is derived from the same name.
In computing and telecommunication, a control character or non-printing character (NPC) is a code point in a character set that does not represent a written character or symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly graphic characters, also known as printing characters, except perhaps for "space" characters. In the ASCII standard there are 33 control characters, such as code 7, BEL, which rings a terminal bell.
In computing, plain text is a loose term for data that represent only characters of readable material but not its graphical representation nor other objects. It may also include a limited number of "whitespace" characters that affect simple arrangement of text, such as spaces, line breaks, or tabulation characters. Plain text is different from formatted text, where style information is included; from structured text, where structural parts of the document such as paragraphs, sections, and the like are identified; and from binary files in which some portions must be interpreted as binary objects.
In ISO/IEC 646 and related standards including ISO 8859 and Unicode, a graphic character, also known as printing character, is any character intended to be written, printed, or otherwise displayed in a form that can be read by humans. In other words, it is any encoded character that is associated with one or more glyphs.
A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectively against the paper with a type element. At the end of the nineteenth century, the term 'typewriter' was also applied to a person who used such a device.
A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists stored as data within a computer file system. In operating systems such as CP/M and DOS, where the operating system does not keep track of the file size in bytes, the end of a text file is denoted by placing one or more special characters, known as an end-of-file (EOF) marker, as padding after the last line in a text file. On modern operating systems such as Microsoft Windows and Unix-like systems, text files do not contain any special EOF character, because file systems on those operating systems keep track of the file size in bytes. Most text files need to have end-of-line delimiters, which are done in a few different ways depending on operating system. Some operating systems with record-orientated file systems may not use new line delimiters and will primarily store text files with lines separated as fixed or variable length records.
A newline is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a sequence of characters, is used to signify the end of a line of text and the start of a new one.
The tab keyTab ↹ on a keyboard is used to advance the cursor to the next tab stop.
The backtick` is a typographical mark used mainly in computing. It is also known as backquote, grave, or grave accent.
The ATASCII character set, from ATARI Standard Code for Information Interchange, alternatively ATARI ASCII, is a character encoding used in the Atari 8-bit family of home computers. ATASCII is based on ASCII, but is not fully compatible with it.
The Friden Flexowriter was a teleprinter produced by the Friden Calculating Machine Company. It was a heavy-duty electric typewriter capable of being driven not only by a human typing, but also automatically by several methods, including direct attachment to a computer and by use of paper tape.
Backspace is the keyboard key that in typewriters originally pushed the carriage one position backwards, and in modern computer systems typically moves the display cursor one position backwards, deletes the character at that position, and shifts back any text after that position by one character.
Perl Compatible Regular Expressions (PCRE) is a library written in C, which implements a regular expression engine, inspired by the capabilities of the Perl programming language. Philip Hazel started writing PCRE in summer 1997. PCRE's syntax is much more powerful and flexible than either of the POSIX regular expression flavors and than that of many other regular-expression libraries.
On computer keyboards, the enter key⌅ Enter and return key↵ Return are two closely related keys with overlapping and distinct functions dependent on operating system and application.
The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use ASCII and derivatives of ASCII. The codes represent additional information about the text, such as the position of a cursor, an instruction to start a new line, or a message that the text has been received.
A whitespace character is a character data element that represents white space when text is rendered for display by a computer.
Many Unicode characters are used to control the interpretation or display of text, but these characters themselves have no visual or spatial representation. For example, the null character is used in C-programming application environments to indicate the end of a string of characters. In this way, these programs only require a single starting memory address for a string, since the string ends once the program reads the null character.
The IBM Selectric was a highly successful line of electric typewriters introduced by IBM on 31 July 1961.
Caret is the name used familiarly for the character ^ provided on most QWERTY keyboards by typing ⇧ Shift+6. The symbol has a variety of uses in programming and mathematics. The name "caret" arose from its visual similarity to the original proofreader's caret, a mark used in proofreading to indicate where a punctuation mark, word, or phrase should be inserted into a document. The formal ASCII standard (X3.64.1977) calls it a "circumflex".