Can anyone tell me what is the symbol used for new line?
In the C language we use '\n' for new line. What do we use in Objective-C?
is it same?
Objective-C is an extension of C. So '\n' works too in Objective-C.
It's the same (\n), but there's a lot more to the topic depending on whether it's just a new line or a new paragraph, what context the text will be processed in, etc. From the documentation (referencing the Cocoa docs here because they cover both Objective-C [implicitly] and Cocoa, since you have the iphone tag on your question):
There are a number of ways in which a line or paragraph break may be represented. Historically \n, \r, and \r\n have been used. Unicode defines an unambiguous paragraph separator, U+2029 (for which Cocoa provides the constant NSParagraphSeparatorCharacter), and an unambiguous line separator, U+2028 (for which Cocoa provides the constant NSLineSeparatorCharacter).
In the Cocoa text system, the NSParagraphSeparatorCharacter is treated consistently as a paragraph break, and NSLineSeparatorCharacter is treated consistently as a line break that is not a paragraph break—that is, a line break within a paragraph. However, in other contexts, there are few guarantees as to how these characters will be treated. POSIX-level software, for example, often recognizes only \n as a break. Some older Macintosh software recognizes only \r, and some Windows software recognizes only \r\n. Often there is no distinction between line and paragraph breaks.
Which line or paragraph break character you should use depends on how your data may be used and on what platforms. The Cocoa text system recognizes \n, \r, or \r\n all as paragraph breaks—equivalent to NSParagraphSeparatorCharacter. When it inserts paragraph breaks, for example with insertNewline:, it uses \n. Ordinarily NSLineSeparatorCharacter is used only for breaks that are specifically line breaks and not paragraph breaks, for example in insertLineBreak:, or for representing HTML <br> elements.
If your breaks are specifically intended as line breaks and not paragraph breaks, then you should typically use NSLineSeparatorCharacter. Otherwise, you may use \n, \r, or \r\n depending on what other software is likely to process your text. The default choice for Cocoa is usually \n.
It's the same, but if you are printing to the console, you should use
NSLog(#"This is a console statement\n on two different lines");
Hope this helps.
It's same dude. Objective-c is superset of c so most of the things from c will work in objective-c too.
Its same.In Objective c "\n" use for new line.
Straight from the dragons mouth.
http://developer.apple.com/library/mac/#documentation/cocoa/conceptual/Strings/Articles/stringsParagraphBreaks.html
Related
Every programming language has their own interpretation of \n and \r.
Unicode supports multiple characters that can represent a new line.
From the Rust reference:
A whitespace escape is one of the characters U+006E (n), U+0072 (r),
or U+0074 (t), denoting the Unicode values U+000A (LF), U+000D (CR) or
U+0009 (HT) respectively.
Based on that statement, I'd say a Rust character is a new-line character if it is either \n or \r. On Windows it might be the combination of \r and \n. I'm not sure though.
What about the following?
Next line character (U+0085)
Line separator character (U+2028)
Paragraph separator character (U+2029)
In my opinion, we are missing something like a char.is_new_line().
I looked through the Unicode Character Categories but couldn't find a definition for new-lines.
Do I have to come up with my own definition of what a Unicode new-line character is?
There is considerable practical disagreement between languages like Java, Python, Go and JavaScript as to what constitutes a newline-character and how that translates to "new lines". The disagreement is demonstrated by how the batteries-included regex engines treat patterns like $ against a string like \r\r\n\n in multi-line-mode: Are there two lines (\r\r\n, \n), three lines (\r, \r\n, \n, like Unicode says) or four (\r, \r, \n, \n, like JS sees it)? Go and Python do not treat \r\n as a single $ and neither does Rust's regex crate; Java's does however. I don't know of any language whose batteries extend newline-handling to any more Unicode characters.
So the takeaway here is
It is agreed upon that \n is a newline
\r\n may be a single newline
unless \r\n is treated as two newlines
unless \r\n is "some character followed by a newline"
You shall not have any more newlines beside that.
If you really need more Unicode characters to be treated as newlines, you'll have to define a function that does that for you. Don't expect real-world input that expects that. After all, we had the ASCII Record separator for a gazillion years and everybody uses \t instead as well.
Update: See http://www.unicode.org/reports/tr14/tr14-32.html#BreakingRules section LB5 for why \r\r\n should be treated as two line breaks. You could read the whole page to get a grip on how your original question would have to be implemented. My guess is by the point you reach "South East Asian: line breaks require morphological analysis" you'll close the tab :-)
The newline character is declared as 0xA from this documentation
Sample: Rust Playground
// c is our `char`
if c == 0xA as char {
println!("got a newline character")
}
So this web page is rendering with these symbols and they are found throughout this website/application but on no other sites. Can anyone tell me
What this symbol is?
Why it is showing up only in one browser?
That character is U+2028 Line Separator, which is a kind of newline character. Think of it as the Unicode equivalent of HTML’s <br>.
As to why it shows up here: my guess would be that an internal database uses LSEP to not conflict with literal newlines or HTML tags (which might break the database or cause security errors), and either:
The server-side scripts that convert the database to HTML neglected to replace LSEP with <br>
Chrome just breaks standards by displaying LSEP as a printing (visible) character, or
You have a font installed that displays LSEP as a printing character that only Chrome detects. To figure out which font it is, right click on the offending text and click “Inspect”, then switch to the “Computed” tab on the right-hand panel. At the very bottom you should see a section labeled “Rendered Fonts” which will help you locate the offending font.
More information on the line separator, excerpted from the Unicode standard, Chapter 5.8, Newline Guidelines (on p. 12 of this PDF):
Line Separator and Paragraph Separator
A paragraph separator—independent of how it is encoded—is used to indicate a
separation between paragraphs. A line separator indicates where a line break
alone should occur, typically within a paragraph. For example:
This is a paragraph with a line separator at this point,
causing the word “causing” to appear on a different line, but not causing
the typical paragraph indentation, sentence breaking, line spacing, or
change in flush (right, center, or left paragraphs).
For comparison, line separators basically correspond to HTML <BR>, and
paragraph separators to older usage of HTML <P> (modern HTML delimits
paragraphs by enclosing them in <P>...</P>). In word processors, paragraph
separators are usually entered using a keyboard RETURN or ENTER; line
separators are usually entered using a modified RETURN or ENTER, such as
SHIFT-ENTER.
A record separator is used to separate records. For example, when exchanging
tabular data, a common format is to tab-separate the cells and to use a CRLF
at the end of a line of cells. This function is not precisely the same as line
separation, but the same characters are often used.
Traditionally, NLF started out as a line separator (and sometimes record
separator). It is still used as a line separator in simple text editors such as
program editors. As platforms and programs started to handle word processing
with automatic line-wrap, these characters were reinterpreted to stand for
paragraph separators. For example, even such simple programs as the Windows
Notepad program and the Mac SimpleText program interpret their platform’s NLF
as a paragraph separator, not a line separator. Once NLF was reinterpreted to
stand for a paragraph separator, in some cases another control character was
pressed into service as a line separator. For example, vertical tabulation VT
is used in Microsoft Word. However, the choice of character for line separator
is even less standardized than the choice of character for NLF. Many Internet
protocols and a lot of existing text treat NLF as a line separator, so an
implementer cannot simply treat NLF as a paragraph separator in all
circumstances.
Further reading:
Unicode Technical Report #13: Newline Guidelines
General Punctuation (U+2000–U+206F) chart PDF
SE: Why are there so many spaces and line breaks in Unicode?
SO: What is unicode character 2028 (LS / Line Separator) used for?
U+2028 on codepoints.net A misprint here says that U+2028 was added in v. 1.1 of the Unicode standard, which is false — it was added in 1.0
I found that in WordPress the easiest way to remove "L SEP" and "P SEP" characters is to execute this two SQL queries:
UPDATE wp_posts SET post_content = REPLACE(post_content, UNHEX('e280a9'), '')
UPDATE wp_posts SET post_content = REPLACE(post_content, UNHEX('e280a8'), '')
The javascript way (mentioned in some of the answers) can break some things (in my case some modal windows stopped working).
You can use this tool...
http://www.nousphere.net/cleanspecial.php
...to remove all the special characters that Chrome displays.
Steps:
Paste your HTML and Clean using HTML option.
You can manually delete the characters in the editor on this page and see the result.
Paste back your HTML in file and save :)
I recently ran into this issue, tried a number of fixes but ultimately I had to paste the text into VIM and there was an extra space I had to delete. I tried a number of HTML cleaners but none of them worked, VIM was the key!
9999years answers is great.
In case you use Symfony with Twig template I would recommend to check for an empty Twig block. In my case it was an empty Twig block with an invisible char inside.
The LSEP char was only displayed on certain device / browser.
On the other I had a blank space above the header and I could not see any invisible char.
I had to inspect the GET request to see that the value 1f18 was before the open html tag.
Once I removed an empty Twig block it was gone.
hope this can help someone one day ...
My problem was similar, it was "PSEP" or "P SEP". Similar issue, an invisible character in my file.
I replaced \x{2029} with a normal space. Fixed. This problem only appeared on Windows Chrome. Not on my Mac.
I agree with #Kapil Bathija - Basically you can copy & paste your HTML code into http://www.nousphere.net/cleanspecial.php and convert it.
Then it will convert the special characters for you - Just remove the spaces in between the words and you will realize you have to press backspace 2x meaning there is an invalid character that can't be translated.
I had the same issue and it worked just fine afterwards.
You can also copy the text, paste it into a HTML editor such as Coda, remove the linebreak, copy it and paste it back into your site.
Video here: https://www.loom.com/share/501498afa7594d95a18382f1188f33ce
Looks like my client pasted HTML into Wordpress after initially creating it with MS-Word. Even deleting the and visible spaces did not fix the issue. The extended characters became visible in vi/vim.
If you don't have vi/vim available, try highlighting from 2 chars before the LSEP to 2 chars after the LSEP; delete that chunk, and re-type the correct characters.
I'm trying to use libunibreak (https://github.com/adah1972/libunibreak) to mark the possible line breaks in some given unicode text.
Libunibreak gives back four possible options for each code unit in some text:
LINEBREAK_MUSTBREAK
LINEBREAK_ALLOWBREAK
LINEBREAK_NOBREAK
LINEBREAK_INSIDEACHAR
Hopefully these are self explanatory. I would expect that MUSTBREAK corresponds to newline characters like LF. However, for any given text Libunibreak always indicates that the last character is MUSTBREAK
So for example with the string "abc", the output would be [NOBREAK,NOBREAK,MUSTBREAK]. For "abc\n" the output would be [NOBREAK,NOBREAK,NOBREAK,MUSTBREAK]. I use the MUSTBREAK attribute to start a new line when drawing text so the first case ("abc") creates an extra linebreak that shouldn't be there.
Is this behaviour what Unicode specifies or is this a quirk of the library implementation I'm using?
Yes, this is what the Unicode line breaking algorithm specifies. Rule LB3 in UAX #14: Unicode Line Breaking Algorithm, section 6.1 "Non-tailorable Line Breaking Rules" says:
Always break at the end of text.
The spec further explains:
[This rule is] designed to deal with degenerate cases, so that there is [...] at least one line break for the whole text.
We are going to digitize a lot of books. We want to mark place of line break in original book without influencing the flow of digital book. Which invisible Unicode charter can be used to mark some special places in a raw file?
(\n will used to indicate end of paragraph)
This is a sentence
in the original book that
I want to mark line
break places.
What is the proper character to replace *:
This is a sentence * in the original book that * I want to mark line *break places.
Unicode has no concept of a hidden character that represents a line break in some original but does not cause line break in rendering. Unicode encodes plain text data, and its control characters for line breaks have an effect when plain text is rendered.
What matters here is how the files will be used. If they need to be processable with plain text editors, then you need to decide: either the line breaks are replicated in default rendering, or they are omitted when creating the file. You can’t make them invisible. And different text editors, like Notepad and Emacs, may well use different line control conventions; one program’s end of line is another program’s end of paragraph.
If the files will only be processed by programs that you create, then you can use whatever conventions you like. The most logical one is this:
“Line and Paragraph Separator. The Unicode Standard provides two unambiguous characters,
U+2028 line separator and U+2029 paragraph separator, to separate lines and
paragraphs. They are considered the default form of denoting line and paragraph boundaries
in Unicode plain text. A new line is begun after each line separator. A new paragraph
is begun after each paragraph separator. As these characters are separator codes, it is not necessary either to start the first line or paragraph or to end the last line or paragraph with them. Doing so would indicate that there was an empty paragraph or line following. The paragraph separator can be inserted between paragraphs of text. Its use allows the creation of plain text files, which can be laid out on a different line width at the receiving end. The line separator can be used to indicate an unconditional end of line.”
http://www.unicode.org/versions/Unicode6.1.0/ch16.pdf (pages 6 and 7 in the PDF)
Beware that U+2028 and U+2029 are generally not understood by text editors. They are suitable for storing data in plain text format. When the text is to be rendered, the rendering software has the option of ignoring the original division into lines and treating U+2028 as equivalent to a space, except if preceded by a hyphen (which poses a problem that cannot be resolved without higher level information: a line that ends with “foo-” and is follod by a line beginning with “bar” could represent the word “foobar” as hyphenated for line breaking, or a hyphenated compound “foo-bar” or, in some cases, the combination “foo- bar”).
Use the line feed character (LF, "\n", 0x0A) and/or maybe carriage return (CR, "\r", 0x0D).
I.e., the regular characters for this purpose.
How are \r and \n different? I think it has something to do with Unix vs. Windows vs. Mac, but I'm not sure exactly how they're different, and which to search for/match in regexes.
They're different characters. \r is carriage return, and \n is line feed.
On "old" printers, \r sent the print head back to the start of the line, and \n advanced the paper by one line. Both were therefore necessary to start printing on the next line.
Obviously that's somewhat irrelevant now, although depending on the console you may still be able to use \r to move to the start of the line and overwrite the existing text.
More importantly, Unix tends to use \n as a line separator; Windows tends to use \r\n as a line separator and Macs (up to OS 9) used to use \r as the line separator. (Mac OS X is Unix-y, so uses \n instead; there may be some compatibility situations where \r is used instead though.)
For more information, see the Wikipedia newline article.
EDIT: This is language-sensitive. In C# and Java, for example, \n always means Unicode U+000A, which is defined as line feed. In C and C++ the water is somewhat muddier, as the meaning is platform-specific. See comments for details.
In C and C++, \n is a concept, \r is a character, and \r\n is (almost always) a portability bug.
Think of an old teletype. The print head is positioned on some line and in some column. When you send a printable character to the teletype, it prints the character at the current position and moves the head to the next column. (This is conceptually the same as a typewriter, except that typewriters typically moved the paper with respect to the print head.)
When you wanted to finish the current line and start on the next line, you had to do two separate steps:
move the print head back to the beginning of the line, then
move it down to the next line.
ASCII encodes these actions as two distinct control characters:
\x0D (CR) moves the print head back to the beginning of the line. (Unicode encodes this as U+000D CARRIAGE RETURN.)
\x0A (LF) moves the print head down to the next line. (Unicode encodes this as U+000A LINE FEED.)
In the days of teletypes and early technology printers, people actually took advantage of the fact that these were two separate operations. By sending a CR without following it by a LF, you could print over the line you already printed. This allowed effects like accents, bold type, and underlining. Some systems overprinted several times to prevent passwords from being visible in hardcopy. On early serial CRT terminals, CR was one of the ways to control the cursor position in order to update text already on the screen.
But most of the time, you actually just wanted to go to the next line. Rather than requiring the pair of control characters, some systems allowed just one or the other. For example:
Unix variants (including modern versions of Mac) use just a LF character to indicate a newline.
Old (pre-OSX) Macintosh files used just a CR character to indicate a newline.
VMS, CP/M, DOS, Windows, and many network protocols still expect both: CR LF.
Old IBM systems that used EBCDIC standardized on NL--a character that doesn't even exist in the ASCII character set. In Unicode, NL is U+0085 NEXT LINE, but the actual EBCDIC value is 0x15.
Why did different systems choose different methods? Simply because there was no universal standard. Where your keyboard probably says "Enter", older keyboards used to say "Return", which was short for Carriage Return. In fact, on a serial terminal, pressing Return actually sends the CR character. If you were writing a text editor, it would be tempting to just use that character as it came in from the terminal. Perhaps that's why the older Macs used just CR.
Now that we have standards, there are more ways to represent line breaks. Although extremely rare in the wild, Unicode has new characters like:
U+2028 LINE SEPARATOR
U+2029 PARAGRAPH SEPARATOR
Even before Unicode came along, programmers wanted simple ways to represent some of the most useful control codes without worrying about the underlying character set. C has several escape sequences for representing control codes:
\a (for alert) which rings the teletype bell or makes the terminal beep
\f (for form feed) which moves to the beginning of the next page
\t (for tab) which moves the print head to the next horizontal tab position
(This list is intentionally incomplete.)
This mapping happens at compile-time--the compiler sees \a and puts whatever magic value is used to ring the bell.
Notice that most of these mnemonics have direct correlations to ASCII control codes. For example, \a would map to 0x07 BEL. A compiler could be written for a system that used something other than ASCII for the host character set (e.g., EBCDIC). Most of the control codes that had specific mnemonics could be mapped to control codes in other character sets.
Huzzah! Portability!
Well, almost. In C, I could write printf("\aHello, World!"); which rings the bell (or beeps) and outputs a message. But if I wanted to then print something on the next line, I'd still need to know what the host platform requires to move to the next line of output. CR LF? CR? LF? NL? Something else? So much for portability.
C has two modes for I/O: binary and text. In binary mode, whatever data is sent gets transmitted as-is. But in text mode, there's a run-time translation that converts a special character to whatever the host platform needs for a new line (and vice versa).
Great, so what's the special character?
Well, that's implementation dependent, too, but there's an implementation-independent way to specify it: \n. It's typically called the "newline character".
This is a subtle but important point: \n is mapped at compile time to an implementation-defined character value which (in text mode) is then mapped again at run time to the actual character (or sequence of characters) required by the underlying platform to move to the next line.
\n is different than all the other backslash literals because there are two mappings involved. This two-step mapping makes \n significantly different than even \r, which is simply a compile-time mapping to CR (or the most similar control code in whatever the underlying character set is).
This trips up many C and C++ programmers. If you were to poll 100 of them, at least 99 will tell you that \n means line feed. This is not entirely true. Most (perhaps all) C and C++ implementations use LF as the magic intermediate value for \n, but that's an implementation detail. It's feasible for a compiler to use a different value. In fact, if the host character set is not a superset of ASCII (e.g., if it's EBCDIC), then \n will almost certainly not be LF.
So, in C and C++:
\r is literally a carriage return.
\n is a magic value that gets translated (in text mode) at run-time to/from the host platform's newline semantics.
\r\n is almost always a portability bug. In text mode, this gets translated to CR followed by the platform's newline sequence--probably not what's intended. In binary mode, this gets translated to CR followed by some magic value that might not be LF--possibly not what's intended.
\x0A is the most portable way to indicate an ASCII LF, but you only want to do that in binary mode. Most text-mode implementations will treat that like \n.
"\r" => Return
"\n" => Newline or Linefeed
(semantics)
Unix based systems use just a "\n" to end a line of text.
Dos uses "\r\n" to end a line of text.
Some other machines used just a "\r". (Commodore, Apple II, Mac OS prior to OS X, etc..)
\r is used to point to the start of a line and can replace the text from there, e.g.
main()
{
printf("\nab");
printf("\bsi");
printf("\rha");
}
Produces this output:
hai
\n is for new line.
In short \r has ASCII value 13 (CR) and \n has ASCII value 10 (LF).
Mac uses CR as line delimiter (at least, it did before, I am not sure for modern macs), *nix uses LF and Windows uses both (CRLF).
In addition to #Jon Skeet's answer:
Traditionally Windows has used \r\n, Unix \n and Mac \r, however newer Macs use \n as they're unix based.
\r is Carriage Return; \n is New Line (Line Feed) ... depends on the OS as to what each means. Read this article for more on the difference between '\n' and '\r\n' ... in C.
in C# I found they use \r\n in a string.
\r used for carriage return. (ASCII value is 13)
\n used for new line. (ASCII value is 10)