Why would one omit the close tag

Question

I keep reading it is poor practice to use the PHP close tag   gt  at the end of the file  The header problem seems irrelevant in the following context  and this is the only good argument so far        Modern versions of PHP set the output buffering flag in php ini   If output buffering is enabled  you can set HTTP headers and cookies after outputting HTML because the returned code is not sent to the browser immediately    Every good practice book and wiki starts with this  rule  but nobody offers good reasons  Is there another good reason to skip the ending PHP tag

User · Answer

As my question was marked as duplicate of this one, I think it's O.K. to post why NOT omitting closing tag ?> can be for some reasons desired.

With complete Processing Instructions Syntax (<?php ... ?>) PHP source is valid SGML document, which can be parsed and processed without problems with SGML parser. With additional restrictions it can be valid XML/XHTML as well.

Nothing prevents you from writing valid XML/HTML/SGML code. PHP documentation is aware of this. Excerpt:

Note: Also note that if you are embedding PHP within XML or XHTML you will need to use the < ?php ?> tags to remain compliant with standards.

Of course PHP syntax is not strict SGML/XML/HTML and you create a document, which is not SGML/XML/HTML, just like you can turn HTML into XHTML to be XML compliant or not.

At some point you may want to concatenate sources. This will be not as easy as simply doing cat source1.php source2.php if you have inconsistency introduced by omitting closing ?> tags.
Without ?> it's harder to tell if document was left in PHP escape mode or PHP ignore mode (PI tag <?php may have been opened or not). Life is easier if you consistently leave your documents in PHP ignore mode. It's just like work with well formatted HTML documents compared to documents with unclosed, badly nested tags etc.
It seems that some editors like Dreamweaver may have problems with PI left open [1].

User · Answer

Pros   Would be logical to close any opened tag  like with other languages  Not only X HT ML tags  but as well curly braces  brackets    Less confusing for beginners    Cons   Avoids headache with adding inadvertently whitespaces after the closing tag  because it breaks the header   function behavior    Some nbsp editors or FTP clients   servers are also known to change nbsp automatically nbsp the end of files  at least  it s their default configuration  PHP manual says closing tag is optional  and Zend even forbids it    Conclusion  I would say that the arguments in favor of omitting the tag look stronger  helps to avoid big headache with header     it s PHP Zend  recommendation    I admit that this isn t the most  beautiful  solution I ve ever seen in terms of syntax consistency  but what could be better

User · Answer

The reason you should leave off the php closing tag    gt   is so that the programmer doesn t accidentally send extra newline chars   The reason you shouldn t leave off the php closing tag is because it causes an imbalance in the php tags and any programmer with half a mind can remember to not add extra white-space   So for your question      Is there another good reason to skip the ending php tag    No  there isn t another good reason to skip the ending php tags   I will finish with some arguments for not bothering with the closing tag    People are always able to make mistakes  no matter how smart they are  Adhering to a practice that reduces the number of possible mistakes is  IMHO  a good idea  PHP is not XML  PHP doesn t need to adhere to XMLs strict standards to be well written and functional  If a missing closing tag annoys you  you re allowed to use a closing tag  it s not a set-in-stone rule one way or the other

User · Answer

Sending headers earlier than the normal course may have far reaching consequences  Below are just a few of them that happened to come to my mind at the moment    While current PHP releases may have output buffering on  the actual production servers you will be deploying your code on are far more important than any development or testing machines  And they do not always tend to follow latest PHP trends immediately  You may have headaches over inexplicable functionality loss  Say  you are implementing some kind payment gateway  and redirect user to a specific URL after successful confirmation by the payment processor  If some kind of PHP error  even a warning  or an excess line ending happens  the payment may remain unprocessed and the user may still seem unbilled  This is also one of the reasons why needless redirection is evil and if redirection is to be used  it must be used with caution  You may get  Page loading canceled  type of errors in Internet Explorer  even in the most recent versions  This is because an AJAX response json include contains something that it shouldn t contain  because of the excess line endings in some PHP files  just as I ve encountered a few days ago  If you have some file downloads in your app  they can break too  because of this  And you may not notice it  even after years  since the specific breaking habit of a download depends on the server  the browser  the type and content of the file  and possibly some other factors I don t want to bore you with   Finally  many PHP frameworks including Symfony  Zend and Laravel  there is no mention of this in the coding guidelines but it follows the suit  and the PSR-2 standard  item 2 2  require omission of the closing tag  PHP manual itself  1 2   Wordpress  Drupal and many other PHP software I guess  advise to do so  If you simply make a habit of following the standard  and setup PHP-CS-Fixer for your code  you can forget the issue  Otherwise you will always need to keep the issue in your mind    Bonus  a few gotchas  actually currently one  related to these 2 characters    Even some well-known libraries may contain excess line endings after   gt   An example is Smarty  even the most recent versions of both 2   and 3   branch have this  So  as always  watch for third party code  Bonus in bonus  A regex for deleting needless PHP endings  replace   s    gt  s    with empty text in all files that contain PHP code

User · Answer

If I understand the question correctly  it has to do with output buffering and the affect this might have on closing ending tags   I am not sure that is an entirely valid question   The problem is that the output buffer does not mean all content is held in memory before sending it out to the client   It means some of the content is   The programmer can purposely flush the buffer  or the output buffer so does the output buffer option in PHP really change how the closing tag affects coding   I would argue that it does not     And maybe that is why most of the answers went back to personal style and syntax

User · Answer

It isn t a tag     But if you have it  you risk having white space after it    If you then use it as an include at the top of a document  you could end up inserting white space  i e  content  before you attempt to send HTTP headers     which isn t allowed

User · Answer

According to the docs  it s preferable to omit the closing tag if it s at the end of the file for the following reason      If a file is pure PHP code  it is preferable to omit the PHP closing tag at the end of the file  This prevents accidental whitespace or new lines being added after the PHP closing tag  which may cause unwanted effects because PHP will start output buffering when there is no intention from the programmer to send any output at that point in the script    PHP Manual   Language Reference    Basic syntax   PHP tags

User · Answer

Well  I know the reason  but I can t show it      For files that contain only PHP code  the closing tag    gt   is never   permitted  It is not required by PHP    and omitting it prevents the   accidental injection of trailing white   space into the response    Source  http   framework zend com manual en coding-standard php-file-formatting html

User · Answer

It s pretty useful not to let the closing   gt  in   The file stays valid to PHP  not a syntax error  and as  David Dorward said it allows to avoid having white space   break-line  anything that can send a header to the browser  after the   gt    For example    lt       header  Content-type  image png         img   imagecreatetruecolor   10  10       imagepng    img     gt   space here   break line here    won t be valid   But    lt       header  Content-type  image png         img   imagecreatetruecolor   10  10        imagepng    img      will   For once  you must be lazy to be secure

User · Answer

In addition to everything that s been said already  I m going to throw in another reason that was a huge pain for us to debug   Apache 2 4 6 with PHP 5 4 actually segmentation faults on our production machines when there s empty space behind the closing php tag  I just wasted hours until I finally narrowed down the bug with strace   Here is the error that Apache throws    core notice   pid 7842  AH00052  child pid 10218 exit signal Segmentation fault  11

User · Answer

There are 2 possible use of php code    PHP code such as class definition or function definition Use PHP as a template language  i e  in views    in case 1  the closing tag is totally unusefull  also I would like to see just 1  one  php open tag and NO  zero  closing tag in such a case  This is a good practice as it make code clean and separate logic from presentation  For presentation case  2   some found it is natural to close all tags  even the PHP-processed ones   that leads to confution  as the PHP has in fact 2 separate use case  that should not be mixed  logic calculus and presentation

User · Answer

Is there another good reason  other than the header problem  to skip the ending php tag    You don t want to inadvertently output extraneous whitepace characters when generating binary output  CSV data  or other non-HTML output

User · Answer

Well  there are two ways of looking at it      PHP code is nothing more than a set of XML processing instructions  and therefore any file with a  php extension is nothing more than an XML file that just so happens to be parsed for PHP code  PHP just so happens to share the XML processing instruction format for its open and close tags  Based on that  files with  php extensions MAY be valid XML files  but they don t need to be    If you believe the first route  then all PHP files require closing end tags  To omit them will create an invalid XML file  Then again  without having an opening  lt  xml version  1 0  charset  latin-1    gt  declaration  you won t have a valid XML file anyway     So it s not a major issue     If you believe the second route  that opens the door for two types of  php files    Files that contain only code  library files for example  Files that contain native XML and also code  template files for example    Based on that  code-only files are OK to end without a closing   gt  tag  But the XML-code files are not OK to end without a closing   gt  since it would invalidate the XML   But I know what you re thinking  You re thinking what does it matter  you re never going to render a PHP file directly  so who cares if it s valid XML  Well  it does matter if you re designing a template  If it s valid XML HTML  a normal browser will simply not display the PHP code  it s treated like a comment   So you can mock out the template without needing to run the PHP code within     I m not saying this is important  It s just a view that I don t see expressed too often  so what better place to share it     Personally  I do not close tags in library files  but do in template files    I think it s a personal preference  and coding guideline  based more than anything hard

User · Answer

It s a newbie coding style recommendation  well-intentioned  and advised by the manual    Eschewing   gt  however solves just a trickle of the common headers already sent causes  raw output  BOM  notices  etc   and their follow-up problems   PHP actually contains some magic to eat up single linebreaks after the   gt  closing token  Albeit that has historic issues  and leaves newcomers still susceptible to flaky editors and unawarely shuffling in other whitespace after   gt   Stylistically some developers prefer to view  lt  php and   gt  as SGML tags   XML processing instructions  implying the balance consistency of a trailing close token       Which btw  is useful for dependency-conjoining class includes to supplant inefficient file-by-file autoloading   Somewhat uncommonly the opening  lt  php is characterized as PHPs shebang  and fully feasible per binfmt misc   thereby validating the redundancy of a corresponding close tag  There s an obvious advise discrepancy between classic PHP syntax guides mandating   gt  n and the more recent ones  PSR-2  agreeing on omission   For the record  Zend Framework postulating one over the other does not imply its inherent superiority  It s a misconception that experts were drawn to   target audience of unwieldy APIs   SCMs and modern IDEs provide builtin solutions mostly alleviating close tag caretaking    Discouraging any use of the   gt  close tag merely delays explaining basic PHP processing behaviour and language semantics to eschew infrequent issues  It is practical still for collaborative software development due to proficiency variations in participants   Close tag variations   The regular   gt  close tag is also known as T CLOSE TAG  or thus  close token   It comprises a few more incarnations  because of PHPs magic newline eating     gt  n    Unix linefeed     gt  r    Carriage return  classic MACs     gt  r n    CR LF  on DOS Win   PHP doesn t support the Unicode combo linebreak NEL  U 0085  however   Early PHP versions had IIRC compile-ins limiting platform-agnosticism somewhat  FI even just used  gt  as close marker   which is the likely historic origin of the close-tag-avoidance  Often overlooked  but until PHP7 removes them  the  regular  lt  php opening token can be validly paired with the rarely used  lt  script gt  as odd closing token  The  hard close tag  isn t even one -- just made that term up for analogy  Conceptionally and usage-wise   halt compiler should however be recognized as close token     HALT COMPILER      gt    Which basically has the tokenizer discard any code or plain HTML sections thereafter  In particular PHAR stubs make use of that  or its redundant combination with   gt  as depicted  Likewise does a void return  infrequently substitute in include scripts  rendering any   gt  with trailing whitespace noneffective  Then there are all kinds of soft   faux close tag variations  lesser known and seldomly used  but usually per commented-out tokens    Simple spacing       gt  to evade detection by PHPs tokenizer  Or fancy Unicode substitutes        U FE56 SMALL QUESTION MARK  U FE65 SMALL ANGLE BRACKET  which a regexp can grasp    Both mean nothing to PHP  but can have practical uses for PHP-unaware or semi-aware external toolkits  Again cat-joined scripts come to mind  with resulting       gt    lt  php concatenations that inline-retain the former file sectioning    So there are context-dependent but practical alternatives to an imperative close tag omission   Manual babysitting of   gt  close tags is not very contemporary either way  There always have been automation tools for that  even if just sed awk or regex-oneliners   In particular      phptags tag tidier      https   fossil include-once org phptags      Which could generally be used to --unclose php tags for third-party code  or rather just fix any  and all  actual whitespace BOM issues    phptags --warn --whitespace   php   It also handles --long tag conversion etc  for runtime configuration compatibility

[php] Why would one omit the close tag?

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