For other uses, see New Line (disambiguation).
Newline (frequently called line ending, end of line (EOL), line feed, or line break) is a control character or sequence of control characters in a character encoding specification (e.g. ASCII or EBCDIC) that is used to signify the end of a and the start of a new one.
Some text editors set this special character when pressing the ↵ Enter key.
When displaying (or printing) a , this control character causes the text editor to show the following characters in a new line.
In the mid-1800s, long before the advent of teleprinters and teletype machines, Morse code operators or telegraphists invented and used Morse code prosigns to encode white space text formatting in formal written text messages.
In particular the Morse prosign represented by the concatenation of two literal textual Morse code "A" characters sent without the normal inter-character spacing is used in Morse code to encode and indicate a new line in a formal text message.
Later in the age of modern teleprinters standardized character set control codes were developed to aid in white space text formatting.
ASCII was developed simultaneously by the International Organization for Standardization (ISO) and the American Standards Association (ASA), the latter being the predecessor organization to American National Standards Institute (ANSI).
During the period of 1963 to 1968, the ISO draft standards supported the use of either CR+LF or LF alone as a newline, while the ASA drafts supported only CR+LF.
The sequence CR+LF was commonly used on many early computer systems that had adopted Teletype machines—typically a Teletype Model 33 ASR—as a console device, because this sequence was required to position those printers at the start of a new line.
The separation of newline into two functions concealed the fact that the print head could not return from the far right to the beginning of the next line in time to print the next character.
Any character printed after a CR would often print as a smudge in the middle of the page while the print head was still moving the carriage back to the first position.
"The solution was to make the newline two characters: CR to move the carriage to column one, and LF to move the paper up."
In fact, it was often necessary to send extra characters—extraneous CRs or NULs—which are ignored but give the print head time to move to the left margin.
Many early video displays also required multiple character times to scroll the display.
On such systems, applications had to talk directly to the Teletype machine and follow its conventions since the concept of device drivers hiding such hardware details from the application was not yet well developed.
Therefore, text was routinely composed to satisfy the needs of Teletype machines.
Most minicomputer systems from DEC used this convention.
CP/M also used it in order to print on the same terminals that minicomputers used.
The Multics operating system began development in 1964 and used LF alone as its newline.
Multics used a device driver to translate this character to whatever sequence a printer needed (including extra padding characters), and the single byte was more convenient for programming.
Perhaps more importantly, the use of LF alone as a line terminator had already been incorporated into drafts of the eventual ISO/IEC 646 standard.
This created conflicts between Windows and Unix-like OSes, whereby files composed on one OS can't be properly formatted or interpreted by another OS (for example a UNIX shell script written in a Windows text editor like Notepad).
The concepts of carriage return (CR) and line feed (LF) are closely associated and can be considered either separately or together.
Although the design of a machine (typewriter or printer) must consider them separately, the abstract logic of software can combine them together as one event.
This is why a newline in character encoding can be defined as CR and LF combined into one (commonly called CR+LF or CRLF).
Some character sets provide a separate newline character code.
EBCDIC, for example, provides an NL character code in addition to the CR and LF codes.
|Operating system||Character encoding||Abbreviation||hex value||dec value||Escape sequence|
|Unix and Unix-like systems (Linux, macOS, FreeBSD, AIX, Xenix, etc.), Multics, BeOS, Amiga, RISC OS, and others||ASCII||LF||0A||10||\n|
|Microsoft Windows, DOS (MS-DOS, PC DOS, etc.), Atari TOS, DEC TOPS-10, RT-11, CP/M, MP/M, OS/2, Symbian OS, Palm OS, Amstrad CPC, and most other early non-Unix and non-IBM operating systems||CR LF||0D 0A||13 10||\r\n|
|Commodore 8-bit machines (C64, C128), Acorn BBC, ZX Spectrum, TRS-80, Apple II series, Oberon, the classic Mac OS, MIT Lisp Machine and OS-9||CR||0D||13||\r|
|QNX pre-POSIX implementation (version < 4)||RS||1E||30||\036|
|Acorn BBC and RISC OS spooled text output.||LF CR||0A 0D||10 13||\n\r|
|Atari 8-bit machines||ATASCII||9B||155|
|IBM mainframe systems, including z/OS (OS/390) and i5/OS (OS/400)||EBCDIC||NL||15||21||\025|
|ZX80 and ZX81 (Home computers from Sinclair Research Ltd)||used a specific non-ASCII character set||NEWLINE||76||118|
- EBCDIC systems—mainly IBM mainframe systems, including z/OS (OS/390) and i5/OS (OS/400)—use NL (New Line, 0x15) as the character combining the functions of line feed and carriage return. The equivalent Unicode character (0x85) is called NEL (Next Line). EBCDIC also has control characters called CR and LF, but the numerical value of LF (0x25) differs from the one used by ASCII (0x0A). Additionally, some EBCDIC variants also use NL but assign a different numeric code to the character. However, those operating systems use a , which stores text files as one record per line. In most file formats, no line terminators are actually stored.
- Operating systems for the CDC 6000 series defined a newline as two or more zero-valued six-bit characters at the end of a 60-bit word. Some configurations also defined a zero-valued character as a colon character, with the result that multiple colons could be interpreted as a newline depending on position.
- RSX-11 and OpenVMS also use a record-based file system, which stores text files as one record per line. In most file formats, no line terminators are actually stored, but the Record Management Services facility can transparently add a terminator to each line when it is retrieved by an application. The records themselves could contain the same line terminator characters, which could either be considered a feature or a nuisance depending on the application. RMS not only stored records, but also stored metadata about the record separators in different bits for the file to complicate matters even more (since files could have fixed length records, records that were prefixed by a count or records that were terminated by a specific character). The bits weren't generic, so while they could specify that CRLF or LF or even CR was the line terminator, it couldn't substitute some other code.
- Fixed line length was used by some early mainframe operating systems. In such a system, an implicit end-of-line was assumed every 72 or 80 characters, for example. No newline character was stored. If a file was imported from the outside world, lines shorter than the line length had to be padded with spaces, while lines longer than the line length had to be truncated. This mimicked the use of punched cards, on which each line was stored on a separate card, usually with 80 columns on each card, often with sequence numbers in columns 73–80. Many of these systems added a carriage control character to the start of the next record; this could indicate whether the next record was a continuation of the line started by the previous record, or a new line, or should overprint the previous line (similar to a CR). Often this was a normal printing character such as # that thus could not be used as the first character in a line. Some early line printers interpreted these characters directly in the records sent to them.
"Paragraph separator" redirects here.
For the symbol also known as a "paragraph sign", see Pilcrow.
The Unicode standard defines a number of characters that conforming applications should recognize as line terminators:
- LF: Line Feed, U+000A
- VT: Vertical Tab, U+000B
- FF: Form Feed, U+000C
- CR: Carriage Return, U+000D
- CR+LF: CR (U+000D) followed by LF (U+000A)
- NEL: Next Line, U+0085
- LS: Line Separator, U+2028
- PS: Paragraph Separator, U+2029
This may seem overly complicated compared to an approach such as converting all line terminators to a single character, for example LF.
However, Unicode was designed to preserve all information when converting a text file from any existing encoding to Unicode and back.
Therefore, Unicode should contain characters included in existing encodings.
As such, it is defined by ECMA 48, and recognized by encodings compliant with ISO/IEC 2022 (which is equivalent to ECMA 35).
C1 control set is also compatible with ISO-8859-1.
The approach taken in the Unicode standard allows round-trip transformation to be information-preserving while still enabling applications to recognize all possible types of line terminators.
Recognizing and using the newline codes greater than 0x7F (NEL, LS and PS) is not often done.
- ECMAScript accepts LS and PS as line-breaks, but considers U+0085 (NEL) whitespace instead of a line-break.
- Windows 10 does not treat any of NEL, LS, or PS as line-breaks in its default text editor, Notepad.
- gedit, the default text editor of the GNOME desktop environment, treats LS and PS as newlines but does not for NEL.
- JSON allows LS and PS characters within strings, while ECMAScript prior to ES2019 treated them as newlines, and therefore illegal syntax.
- YAML no longer recognizes them as special as of version 1.2, in order to be compatible with JSON.
The Unicode characters U+2424 (SYMBOL FOR NEWLINE, ␤), U+23CE (RETURN SYMBOL, ⏎), U+240D (SYMBOL FOR CARRIAGE RETURN, ␍) and U+240A (SYMBOL FOR LINE FEED, ␊) are intended for presenting a user-visible character to the reader of the document, and are thus not recognized themselves as a newline.
An escape sequence is a combination of characters which represents no text; instead of being displayed (as text) it is supposed to be intercepted by the program and a special function is supposed to be performed.
Escape sequences are also used to handle (set, search, replace, etc.) special characters.
In programming languages
"\n" redirects here.
For the similar number notation, see \nnn (disambiguation).
To facilitate the creation of portable programs, programming languages provide some abstractions to deal with the different types of newline sequences used in different environments.
However, these are not required to be equivalent to the ASCII LF and CR control characters.
The C standard only guarantees two things:
- Each of these escape sequences maps to a unique implementation-defined number that can be stored in a single char value.
- When writing to a file, device node, or socket/fifo in text mode, '\n' is transparently translated to the native newline sequence used by the system, which may be longer than one character. When reading in text mode, the native newline sequence is translated back to '\n'. In binary mode, no translation is performed, and the internal representation produced by '\n' is output directly.
On Unix platforms, where C originated, the native newline sequence is ASCII LF (0x0A), so '\n' was simply defined to be that value.
With the internal and external representation being identical, the translation performed in text mode is a no-op, and Unix has no notion of text mode or binary mode.
This has caused many programmers who developed their software on Unix systems simply to ignore the distinction completely, resulting in code that is not portable to different platforms.
The C library function fgets() is best avoided in binary mode because any file not written with the Unix newline convention will be misread.
Also, in text mode, any file not written with the system's native newline sequence (such as a file created on a Unix system, then copied to a Windows system) will be misread as well.
Another common problem is the use of '\n' when communicating using an Internet protocol that mandates the use of ASCII CR+LF for ending lines.
Writing '\n' to a text mode stream works correctly on Windows systems, but produces only LF on Unix, and something completely different on more exotic systems.
Using "\r\n" in binary mode is slightly better.
Many languages, such as C++, Perl, and Haskell provide the same interpretation of '\n' as C. C++ has an alternative I/O model where the manipulator std::endl can be used to output a newline (and flushes the stream buffer).
In contrast to C, these are guaranteed to represent the values U+000D and U+000A, respectively.
The Java I/O libraries do not transparently translate these into platform-dependent newline sequences on input or output.
Instead, they provide functions for writing a full line that automatically add the native newline sequence, and functions for reading lines that accept any of CR, LF, or CR+LF as a line terminator (see ).
The method can be used to retrieve the underlying line separator.
Python permits "Universal Newline Support" when opening a file for reading, when importing modules, and when executing a file.
In PHP, to avoid portability problems, newline sequences should be issued using the PHP_EOL constant.
Example in C#:
Issues with different newline formats
Even though the control characters are unambiguously defined in the corresponding character encoding table used by a text file, there still is an issue: there are different conventions to set and display a line break.
To denote a single line break, Unix programs use line feed, whose hexadecimal value in ASCII is 0a, while most programs common to MS-DOS and Microsoft Windows use carriage return+line feed, whose hexadecimal value in ASCII is 0d 0a.
In ASCII, carriage return is a distinct control character.
The different newline conventions cause text files that have been transferred between systems of different types to be displayed incorrectly.
Text in files created with programs which are common on Unix-like or classic Mac OS, appear as a single long line on most programs common to MS-DOS and Microsoft Windows because these do not display a single line feed or a single carriage return as a line break.
Conversely, when viewing a file originating from a Windows computer on a Unix-like system, the extra CR may be displayed as a second line break, as ^M, or as <cr> at the end of each line.
Furthermore, programs other than text editors may not accept a file, e.g. some configuration file, encoded using the foreign newline convention, as a valid file.
The problem can be hard to spot because some programs handle the foreign newlines properly while others do not.
On a Unix-like system, the command cat -v myfile.txt will send the file to stdout (normally the terminal) and make the ^M visible, which can be useful for debugging.
Modern text editors generally recognize all flavours of CR+LF newlines and allow users to convert between the different standards.
Web browsers are usually also capable of displaying text files and websites which use different types of newlines.
Even if a program supports different newline conventions, these features are often not sufficiently labeled, described, or documented.
Typically a menu or combo-box enumerating different newline conventions will be displayed to users without an indication if the selection will re-interpret, temporarily convert, or permanently convert the newlines.
Some programs will implicitly convert on open, copy, paste, or save—often inconsistently.
Most textual Internet protocols (including HTTP, SMTP, , IRC, and many others) mandate the use of ASCII CR+LF ('\r\n', 0x0D 0x0A) on the protocol level, but recommend that tolerant applications recognize lone LF ('\n', 0x0A) as well.
Despite the dictated standard, many applications erroneously use the C newline escape sequence '\n' (LF) instead of the correct combination of carriage return escape and newline escape sequences '\r\n' (CR+LF) (see section Newline in programming languages above).
This accidental use of the wrong escape sequences leads to problems when trying to communicate with systems adhering to the stricter interpretation of the standards instead of the suggested tolerant interpretation.
The standard Internet Message Format for eMail states: CR and LF MUST only occur together as CRLF; they MUST NOT appear independently in the body.
The can automatically convert newlines in files being transferred between systems with different newline representations when the transfer is done in "ASCII mode".
However, transferring binary files in this mode usually has disastrous results: any occurrence of the newline byte sequence—which does not have line terminator semantics in this context, but is just part of a normal sequence of bytes—will be translated to whatever newline representation the other system uses, effectively corrupting the file.
FTP clients often employ some heuristics (for example, inspection of ) to automatically select either binary or ASCII mode, but in the end it is up to users to make sure their files are transferred in the correct mode.
If there is any doubt as to the correct mode, binary mode should be used, as then no files will be altered by FTP, though they may display incorrectly.
Conversion between newline formats
Text editors are often used for converting a text file between different newline formats; most modern editors can read and write files using at least the different ASCII CR/LF conventions.
For example, the editor Vim can make a file compatible with the Windows Notepad text editor.
Editors can be unsuitable for converting larger files or bulk conversion of many files.
For larger files (on Windows NT/2000/XP) the following command is often used:
Special purpose programs to convert files between different newline conventions include unix2dos and dos2unix, mac2unix and unix2mac, mac2dos and dos2mac, and flip.
A DOS/Windows text file can be converted to Unix format by simply removing all ASCII CR characters with
or, if the text has only CR newlines, by converting all CR newlines to LF with
The command can identify the type of line endings:
The Unix egrep (extended grep) command can be used to print filenames of Unix or DOS files (assuming Unix and DOS-style files only, no Mac OS):
Other tools permit the user to visualise the EOL characters:
Two ways to view newlines, both of which are self-consistent, are that newlines either separate lines or that they terminate lines.
If a newline is considered a separator, there will be no newline after the last line of a file.
Some programs have problems processing the last line of a file if it is not terminated by a newline.
On the other hand, programs that expect newline to be used as a separator will interpret a final newline as starting a new (empty) line.
Conversely, if a newline is considered a terminator, all text lines including the last are expected to be terminated by a newline.
If the final character sequence in a text file is not a newline, the final line of the file may be considered to be an improper or incomplete text line, or the file may be considered to be improperly truncated.
In text intended primarily to be read by humans using software which implements the word wrap feature, a newline character typically only needs to be stored if a line break is required independent of whether the next word would fit on the same line, such as between paragraphs and in vertical lists.
Therefore, in the logic of word processing and most text editors, newline is used as a paragraph break and is known as a "hard return", in contrast to "soft returns" which are dynamically created to implement word wrapping and are changeable with each display instance.
In many applications a separate control character called "manual line break" exists for forcing line breaks inside a single paragraph.
Reverse and partial line feeds
- ASA carriage control characters
- C0 and C1 control codes
- Line starve
- Page break
- Carriage return
- Enter key
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Newline.