Is a new line = \n OR \r\n?

Question

I've seen many developers use different methods to split a string by new lines, but i'm confused which is the correct: \r\n OR \n only?

Answer 1

\n is used for Unix systems (including Linux, and OSX).

\r\n is mainly used on Windows.

\r is used on really old Macs.

PHP_EOL constant is used instead of these characters for portability between platforms.

Answer 2

The given answer is far from complete. In fact, it is so far from complete that it tends to lead the reader to believe that this answer is OS dependent when it isn't. It also isn't something which is programming language dependent (as some commentators have suggested). I'm going to add more information in order to make this more clear. First, lets give the list of current new line variations (as in, what they've been since 1999):

• \r\n is only used on Windows Notepad (fixed as of 2018), the DOS command line (PowerShell handles \n only just fine; as well as most modern versions of DOS-era command line applications [such as more]), most of the Windows API written before ~2000, and some (older) Windows apps (mostly because they use the Windows API).
• YMMV for .ps1, .bat, and .cmd scripts.
• Oddly enough, TCP/IP uses \r\n. This means that most web protocols (including HTTP itself) use \r\n as noted by Raatje. There are definitely times that this matters for you as a PHP programmer.
• \n is used for all other systems, applications and the content of webpages/email.

You'll notice that I've put most Windows apps in the \n group which may be slightly controversial but before you disagree with this statement, please grab a UNIX formatted text file and try it in 10 web friendly Windows applications of your choice (which aren't listed in my exceptions above). What percentage of them handled it just fine? You'll find that they (practically) all implement auto detection of line endings or just use \n because, while Windows may use \r\n, the Internet and most other OSes just use \n. Therefore, it is best practice for applications to use \n alone if you want your output to be Internet friendly.

PHP also defines a newline character called PHP_EOL. This constant is set to the OS specific newline string for the machine PHP is running on (\r\n for Windows and \n for everything else). This constant is not very useful for webpages and should be avoided for HTML output or for writing most text to files. It becomes VERY useful when we move to command line output from PHP applications because it will allow your application to output to a terminal Window in a consistent manner across all supported OSes.

If you want your PHP applications to work from any server they are placed on, the two biggest things to remember are that you should always just use \n unless it is terminal output (in which case you use PHP_EOL) and you should also ALWAYS use / for your path separator (not \). The third thing to look out for is drive letters in path strings, if allowed, which may be tricky depending on what you're doing.

The even longer explanation:

An application may choose to use whatever line endings it likes regardless of the default OS line ending style. If I want my text editor to print a newline every time it encounters a period that is no harder than using the \n to represent a newline because I'm interpreting the text as I display it anyway. IOW, I'm fiddling around with measuring the width of each character so it knows where to display the next so it is very simple to add a statement saying that if the current char is a period then perform a newline action (or if it is a \n then display a period).

Aside from the null terminator, no character code is sacred and when you write a text editor or viewer you are in charge of translating the bits in your file into glyphs (or carriage returns) on the screen. The only thing that distinguishes a control character such as the newline from other characters is that most font sets don't include them (meaning they don't have a visual representation available).

That being said, if you are working at a higher level of abstraction then you probably aren't making your own textbox controls. If this is the case then you're stuck with whatever line ending that control makes available to you. Even in this case it is a simple (and fairly quick) matter to automatically detect the line ending style of any string and adjust accordingly.

Answer 3

If you are programming in PHP, it is useful to split lines by \n and then trim() each line (provided you don't care about whitespace) to give you a "clean" line regardless.

foreach($line in explode("\n", $data))
{
    $line = trim($line);
    ...
}

Answer 4

For php, \n should work for you!

http://php.net/manual/en/language.types.string.php