ob_start(); // เป็นการประกาศเพื่อให้โปรแกรม สำรองเนื้อที่ในหน่วยความจำมาเพื่อรองรับการใช้งานของ object ต่าง ๆ ที่จะเกิดขึ้นกับโปรแกรมเมื่อมีการทำงาน. ob_start is a PHP function which turns output buffering on. the buffer is emptied and sent out. Session variables are set with the PHP global variable: $_SESSION. buffer. output_compression to 0 or Off; 3) setting Apache variables such as "no-gzip" either through apache_setenv () or through entries in . APC is an opcode cache: The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. Some PHP programmers put ob_start () on the first line of all of their code*, and I'm pretty certain that's what going on here. 4 ob_start(); in php? 1 PHP die function. ini file? If output_buffering is turned on, then PHP will buffer almost the entire page, so what's the point in creating yet another buffer using ob_start? @true PHP is already buffering that entire page, so wouldn't ob_start be. gzgets — Get line from file pointer. Using output buffering. This tells PHP to store any output generated by your script in a buffer instead of sending it to the browser. Then, `flush ()` flushes the output buffer and forces the server to send the data to the browser immediately. php_value output_buffering On php_value output_handler mb_output_handler The code is for Apache servers, i hope this helps out some of you out there :)PHP ob_start () for file caching. ob_start ( callable $callback = null, int $chunk_size = 0, int $flags = PHP_OUTPUT_HANDLER_STDFLAGS ): bool. Definition and Usage. If "URL include wrappers" are enabled in PHP, you can specify. Given an array associating expressions with callbacks, returns a string where all matches of each expression are replaced with the substring returned by the callback. PHP7. A callback function can be passed in to do processing on the contents of the buffer before it gets flushed from the buffer. For some reason the rest of the code of the page continues to execute after the header () method redirect. 1) ob_flush (), flush () in any combination with other output buffering functions; 2) changes to php. For this reason, any code inside the target file which should be executed as PHP code must be enclosed within valid PHP start and end tags . The former specifies a callback to handle output as it's buffered, and the latter specifies the size of the chunks of output to handle. If output buffering is in effect it returns an associative array containing the status of buffering. This new value can be stored in a file, database or as a session variable, etc. Here is the example on php. Edit: I was reading the comments on the manual page and came across a bug that states that ob_implicit_flush does not work and the following is a workaround for it:. Note: HTTP/1. If you use XAMPP for instance, you can go to this link and check if output buffering is on or off. This parameter can be used to limit the number of stack frames printed. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more. The function ob_start turns output buffering on. The php script inherits your environment when you run it from shell, but not when you run it from the web. An optional output_callback function may be specified. This question is in a collective: a subcommunity defined by tags with relevant content and experts. Yes, you can call it more than once. It creates a new buffer each time however, so be careful. A few common output buffering functions: ob_start() turns on output buffering. This question is in a collective: a subcommunity defined by tags with relevant content and experts. Shell scripts that start with #!/usr/bin/bash return their output properly. 2) The server sets the cookie on the user’s computer. ob_start() triggers output buffering which stores all output in a buffer for later use. Why ob_start() solves the header() error? 2. A better way to do this is to use the first two parameters accepted by ob_start: output_callback and chunk_size. Turn on output buffering at the top of your script with ob_start (). any program written in PHP will be executed stepwise, one statement after another, which makes processing comparatively slow compared to others. The callback parameter may be bypassed by passing a null value. PHP’s ob_start() and ob_get_clean() are useful for buffering output of printed content and so forth, but I use them very rarely and tend to forget their order/syntax. ob_start. The output level is. จะเห็นว่าโค้ดด้านบนนี่ PHP แยกอยู่ของ PHP HTML แยกอยู่ของ HTML ทำให้ดูโค้ดได้ง่ายเวลามันอยู่ใน editor. This function takes a string as a parameter and should return a string. use_trans_sid. Description ¶. satishinnovstudio July 1, 2022, 8:37am 5. And something like this at the end of your page: <?php ob_end_flush (); ?>. ";php; ob-start; or ask your own question. wrap the function to be executed in the end, after php close the connection. . Tôi có 1 ví dụ đơn giản như sau: 出力バッファはスタッカブルであり、このため、他の ob_start() がアクティブの間に ob_start() をコールすることが可能です。この場合、 ob_end_flush() を適切な回数コールするようにしてください。 複数の出力コールバック関数がアクティブの場合、 ネストした. Perhaps you can move that part out of the conditional or try rewriting it to where you write the data to the object and then call renderOutput() and this method would have your ob calls in the proper order. The output buffer must be started by ob_start () with PHP_OUTPUT_HANDLER_CLEANABLE flag. it will work as you would use ob_start with no. I'm using ob_flush() for this. ini and try to set it's value to "none" if possible. Parameters. PHP output buffering using ob_start(): What happens on termination of the script? Hot Network Questions Wind farms that wind up in the wind, and then unwind producing energy when the wind is still Zassenhaus's Butterfly Lemma How high of correlation coefficient of feature with target variable is considered too high?. Hot Network Questions Applies f to all locations other than the specified locationob_get_status — Get status of output buffers. Ob _ start function is used to create an output buffer in PHP, as we are already aware that PHP is an interpreted language, i. The path or an open stream resource (which is automatically closed after this function returns) to save the file to. Solution for this is to store your form in a variable then return it,To create a new output buffer and start writing to it, call ob_start(). Use the file_put_contents() function to save the output of the PHP file. Apr 6, 2020 at 16:59. Just call flush whenever you want to force the content to the browser. <?php. A timer on the command line, which clears the line every tick, could be construed as follows:the ob_gzhandler is a callback function which takes the contents from your output buffer and compresses the data before outputting it. A callback function can be passed to the function to process the contents of the buffer before it is flushed from the buffer. About;. In other words, it creates the buffer (invisible holding. Just make sure that you call ob_end_flush () the appropriate number of times. So the echo output will be buffered. Output buffers are stackable, that is, you may call ob_start () while another ob_start () is active. php"); The function ob_start () will turn output buffering on. How to pass a callback function with parameters for ob_start in PHP? Hot Network Questions Creating buffer for MultiPolygon that covers all its surroundings in QGIS Should I send a PDF or Google Drive link to professors? Build a culture of Accountability Novel: Hidden (floating?) island with aptitude tests and sterilization after multiple. Output Control Functions. W3Schools offers free online tutorials, references and exercises in all the major languages of the web. This is it! Now, you can successfully redirect where you want. x and PHP 5. One of PHP_OUTPUT_HANDLER_START (0), PHP_OUTPUT_HANDLER_CONT (1) or PHP_OUTPUT_HANDLER_END (2) name: Name of active output handler or ' default output handler' if none is set: del: Erase-flag as set by ob_start() If called with full_status = true an array with one element for each active output buffer level is returned. 1. You may need to also investigate whether you need to length the time limit for PHP scripts. php from server and the code worked well with all other php files. If output buffering is still active when. ob_end_flush (): bool. These will either be a built-in save handler provided by default or by PHP extensions (such as. 0. However, like I mentioned, if the webserver is. php". ob_implicit_flush — Turn implicit flush on/off. We have built a prototype application in PHP and JS using Server-Sent Events (single AJAX requests, multiple streamed events sent by event handlers in PHP). I would guess you're calling plugin_rvce_options_page () somewhere in the root of the functions. I get binary garbage. As you can notice, exit() is used in the example above. Output buffering should be taking place inside your shortcode. Syntax ob_get_level(): int Parameter. Once you call ob_start(), then only buffering starts, and all your echo etc. However I see my echos coming all at once nevertheless. 0. 출력 버퍼링이 켜져 있는 동안 헤더를 제외한 스크립트의 모든 출력을 내부 버퍼에 저장하며 실제 전송하지 않는다. この記事では「 PHPのob_startでまとめて結果出力!シンプル解説で最短理解 」といった内容について、誰でも理解できるように解説します。この記事を読めば、あなたの悩みが解決するだけじゃなく、新たな気付きも発見できることでしょう。お悩みの方はぜひご一読ください。1. Esta função irá ativar o buffer de saída. If output_callback returns FALSE original input is sent to the browser. 2. Something like this: <?php include 'MPDF57/mpdf. ob_start を理解するためにはまず PHP (PHP: Hypertext Preprocessor) の特徴を知っておく必要があります。 PHP は今では汎用言語として利用されていますが、元々はただの HTML 用のテンプレートツールであり、今でも HTML に埋め込むような構文を特徴としています。I'm generating a ton of XML that is to be passed to an API as a post variable when a user click on a form button. You probably need to include the fully qualified domain and path to the new url. Code may be surrounded in a try block, to facilitate the catching of potential exceptions. phase. How to Use the ob_get_clean() Function. 1. So, until browsers begin to show buffered content. I prefer this one-liner to using ob_start and ob_get_clean(). gzgetss — Get line from gz-file pointer and strip HTML tags. Flush your output at any time with ob_flush (), and the content will be sent to the browser. ob_end_flush — Flush (send) the output buffer and turn off output buffering. I found ob_start() and ob_get_clean() in php manual to achieve this. Learn how to use the ob_start () function in PHP to start output buffering and modify your output before sending it to the client. Take a look at very simple example for PHP 5. flush — Flush system output buffer. Confused why code will only work with ob_start(); 0. php" will parse the variables and HTML, but not directly output now. Make sure your ROOT translates to absolute path to the file (with domain and if you use one). Then I am using file_put_contents() to create the page with that generated content. 1. if I remove ob_start(); and ob_end_clean() at least its printing menu without CSS. ob_gzhandler() Used as a callback function for ob_start() to compress the contents of the buffer when sending it to the browser: ob_implicit_flush() Turns implicit flushing on or off: ob_list_handlers() Returns an array of callback function names that are being used by the topmost output buffer: ob_start() When the return parameter is used, this function uses internal output buffering prior to PHP 7. 公式マニュアルの説明では「出力のバッファリングを有効にする」とあるのですが、この「バッファリング」が実際どういった動作をするものなのか分かりにくいので簡単な図を書いてみました。 ob_flush (): bool. . PHPは、WEBブラウザという手近な実行環境を持つプログラミング言語です。. 0. 2. ob_start (); echo "This output will not be sent to the browser"; ob_end_clean (); echo "This output will be sent to the browser"; ?>. That is, assume that you have 10KB of. ob_start を理解するためにはまず PHP (PHP: Hypertext Preprocessor) の特徴を知っておく必要があります。 PHP は今では汎用言語として利用されていますが、元々はただの HTML 用のテンプレートツールであり、今でも HTML に埋め込むような構文を特徴としています。 I'm generating a ton of XML that is to be passed to an API as a post variable when a user click on a form button. If the optional parameter erase is set to FALSE, the buffer will not be deleted until the script finishes (as of PHP 4. Instead its stored internally. To change this value you can either set it in php. Collectives™ on Stack Overflow. PHP가 사용하는 백엔드 (CGI, 웹 서버 등)에 관계 없이 PHP의 출력 버퍼를 비웁니다. Tôi nhắc đến cơ chế cache vì các hàm ob_start (), ob_get_contents (), ob_clean (), ob_end_flush () sẽ hỗ trợ chúng ta trong quá trình thực hiện cơ chế. It will work. I try with DOMPDF, but I have a problem with defining the string. See the syntax, usage, and examples of the. ob_start — Ausgabepufferung aktivieren. Some PHP code using output buffering functions. Hàm ob_end_clean sẽ giải phóng bộ nhớ đệm mà không in ra gì. 이는 사실상 모든 출력을 사용자 브라우저에 보냅니다. Just make sure that you call ob_end_flush () the appropriate number of times. 출력 버퍼링이 켜져 있는 동안 헤더를 제외한 스크립트의 모든 출력을 내부 버퍼에 저장하며 실제 전송하지 않는다. 5. This function will turn output buffering on. The ob_get_contents() function is a built-in function in PHP that allows you to get the contents of the output buffer. The optional separator parameter sets the field delimiter (one single-byte character only). can please elaborate… how to kill. 5. Contents of the output buffer. The PHP ob_start() function turns on the output buffering. g. Let's implement PHP 's ob_start and ob_get_contents functions in python3. Definition and Usage. Remove space between Location and : --> header ("Location ( remove space ): home. However it would be good to see such function to get the real speed. Thought so, your issue is you're not setting your value login. We will take a look at the. qualityBasic usage getting content between buffers and clearing, Nested output buffers, Running output buffer before any content, Processing the buffer via a callback, Using Output buffer to store contents in a file, useful for reports, invoices etc, Stream output to client, Capturing the output buffer to re-use later, Typical usage and reasons for using ob_startI have PHP (CGI) and Apache. 結果. However, the problem is, it parses the PHP include() and stores only the HTML content. 0. Thank you for your help! If the status of the bug report you submitted changes, you will be notified. here is my code:ob_start(); ob_end_flush(); flush(); It took some time to come up with the above solution however I can confirm with CURL that it is working as expected. Here's my problem. The ob_start () function creates an output buffer. Problem with ob_start function in php. Its goal is to provide a free, open, and robust framework for caching and optimizing PHP intermediate code. It doesn't affect db connection. This function will turn output buffering. [2007-08-29 17:15 UTC] ce at netage dot bg Description: ----- it is actually a duplicate problem with 40429, but since you have closed the bug I cannot reopen it, but it is still present with all versions including the new 5. Also, you can use the header() function with ob_start() and ob_end_flush(), like this:To solve this problem, we have to store the header in a buffer and send the buffer at the end of the script, so to store the header in the buffer, we will use the php ob_start () function and to clean the buffer, we will use the ob_end_flush () function. ob_start is a PHP function which turns output buffering on. ob_start() is printing outputs without ending of ob_get_flush() 1. Worst-case scenario, I'll try bumping my output_buffering value or use ob_start() and ob_end_flush() to the starts and ends of my files. Check network response to css request in browser's developer tools ( F12 usually). Output streaming with PHP ob_start & ob_get_clean. The proper solution to the "Headers already sent" problem is described in a previous thread. ob_start ( callable $callback = null, int $chunk_size = 0, int $flags = PHP_OUTPUT_HANDLER_STDFLAGS ): bool. Start output buffering using the PHP ob_start() function. Just call flush whenever you want to force the content to the browser. Before ob_gzhandler() actually sends compressed data, it determines what type of content encoding the browser will accept ("gzip", "deflate" or none at all) and will return its output. 4 ob_* functions. We hope this article has been informative and useful in understanding the ob_gzhandler. You can use the library like so:What is ob_start() function in PHP - In 5 MinutesIn this lecture, we are going to learn how to use the ob_start() function in PHP. Simply having ob_start('ob_gzhandler'); will suffice. when this sample web page loads, it checks cached file from /cache folder. cache file created for the visited url and if there is a file I will print its content out. Otherwise ob_clean () will not work. So the echo output will be buffered. You need to kill the script after a header redirect or the code will keep running. 7. To start an output buffer, we can use the ob_start() function. It deals with text (mostly) produced by php. output_callback. I try with DOMPDF, but I have a problem with defining the string. From the manual: "Output buffers are stackable, that is, you may call ob_start () while another ob_start () is active. If the output buffering is not active or if there is no content in the buffer then it will return “false”. The output buffer must be started by ob_start () with PHP_OUTPUT_HANDLER_CLEANABLE and. ob_start ()를 여러번 호출해도 오류는 발생하지 않는다. ob_end_flush () turns off output buffering and sends the buffered data to the output, while flush () forces PHP to flush the output buffer immediately, sending. The page is a receipt, so some of its entries are variables. PHP Collective Join the discussion. Sure it's easier to learn (if for no other reason than the voluminous amount of examples), and it will be around for a while, but it's a good idea to learn using a library that won't be going away. . ob_end_flush — Flush (send) the output buffer and turn off output buffering. 2. Then, you can use ob_flush and flush to keep flushing the output. 2. Courses. I also shell_exec() shell scripts which use PHP CLI. ob_get_level returns the current output buffering level. . ob_start starts output buffering. image. The Overflow Blog The AI assistant trained on. W3Schools offers free online tutorials, references and exercises in all the major languages of the web. ob_end_clean, ob_end_flush, ob_clean, ob_flush and ob_start may not be called from a callback function. // Start output buffer. The output buffer must be started by ob_start () with PHP_OUTPUT_HANDLER_CLEANABLE and. First, call ob_start() at the beginning of your script to turn on output buffering. 3. By default ( limit = 0) it prints all. At the start yes, but i cant get it to work. separator. Yes it is, you really don't need the else ob_start() part, nor the gzip check. ob_list_handlers — List all output handlers in use. image. It can likewise be engaged with a call to ob_start(); atop the invocation script. PHP output buffer issue when using ob_gzhandler and ob_clean together. Using ob_start certainly will affect the load times of your pages -- not "the performance of your PHP script", which is IMHO a totally misleading expression. 0). If you want to further process the buffer's contents you have to call ob_get_contents () before ob_end_clean () as the buffer contents are discarded when ob_end_clean () is called. php) into another script (let's say b. You need to kill the script after a header redirect or the code will keep running. php) and store the output in an HTML file (static_content. If you're using mod_php, you can write incrementally out to the. While output buffering is active no output is sent from the script (other than headers), instead the output is stored in an internal buffer. You need to turn output buffer on before include, get the content of the buffer and use it for the generation of pdf. The output buffer must be started by ob_start () with PHP_OUTPUT_HANDLER_FLUSHABLE flag. PHP CLI no longer had the CGI environment variables to. PHP ob_start() Function. ob_end_clean modifies variables as well. ob_start not working in PHP 5. Finally we call ob_end_flush to flush. ini config file and looking for the output buffering configuration setting. The ob_get_contents () function in PHP returns the contents of the output buffer as a string. Finally we call ob_end_flush to flush. I'll explain: Here is a 'hello world' script for dompdf: require_once("In case you have done already HTML output prior the use of setcookie you need to find the place where your HTML output started. The ob_start() function is used to create a new output buffer, and you can immediately start writing to it by printing out content as normal. PHP is a server scripting language, and a powerful tool for making dynamic and interactive Web pages. you have to use the new aliases instead of using the PHP 7. I think that function will be prone to further bugs, therefor using ob_start/ob_end_clean is easier to comprehend and better for future code maintenance. PHP ob_start() function works by catching all output to buffer and then implicitly output this buffer on script end. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more. Definition and Usage. ob_gzhandler — ob_start callback function to gzip output buffer. Using the browser. However, certain Microsoft programs (I'm looking at you, Access 97), will fail to recognize the CSV properly unless each line ends with \r . Cách dùng ob start , ob flush (), flush () Trong PHP vốn đã chạy nhanh nay còn có thêm cơ chế cache làm cho ngôn ngữ PHP ngày càng hoàn hảo. Steps: Send new value to phpScript1 with clientScript1. So i checked the ranking. php’); ob_end_flush(); //this has to be the last line of your page?> 2. gzgetc — Get character from gz-file pointer. I don't know why this would fix it when my current output_buffering value of 4096 doesn't, and I understand that this workaround comes with its own issues. it will work as you would use ob_start with no. The output may be caught by another output buffer or, if there are no other output buffers, sent directly to the browser. If multiple output callback functions are. There are two ways that I can think of at this moment. So every time you do an echo, the output of that is added to the buffer. It’s actually very simple:Alternatively, not to think about a newline or space somewhere in the file, you can buffer the output. MAIS d'autres ne sont pas capable de décompresser la page, comme :After creating a page in php, I am using mpdf to create a pdf that appears like the page. ฟังก์ชัน ob_start () เปิดบัฟเฟอร์การส่งออก (output) เป็น function ของ PHP ที่ไว้ประการใช้ output buffering จะใช้คู่กับ function ob_end_flush () บัฟเฟอร์เอาต์พุตสามารถ. gzfile — Read entire gz-file into an array. ob_end_clean(), ob_end_flush(), ob_clean(), ob_flush() and ob_start() may not be called from a callback function. PHP Collective Join the discussion. This is documented in the manual : Some web servers (e. If multiple output callback functions are active, output is being filtered sequentially through each of them in nesting order. Push your web development skills to the next level, through expert screencasts on PHP, Laravel, Vue, and much more. It doesn't affect db connection. ob_start() flushed automatically when PHP script ends. display members' bar or what) because they will be cached as well. No available working or. 0. any program written in. Description ¶. This question is in a collective: a subcommunity defined by tags with relevant content and experts. ob_startTurn on output buffering (PHP 4, PHP 5) bool ob_start ( [callback output_callback [, int chunk_size [, bool erase]]] ) This function will turn output buffering on. You can call ob_start () more than once in your script. If there is no cached file, it calls ob_start () and creates a . net ob-start function description. Buffer Simple String Using the ob_start Method Then Get Data Using the ob_get_contents Method in PHP. Eg. This function is intended to be passed as a callback to ob_start (). With the help of this. answered Jan 4, 2014 at 7:45. The output buffer must be started by ob_start () with PHP_OUTPUT_HANDLER_CLEANABLE and PHP_OUTPUT_HANDLER_REMOVABLE flags. We hope this article has been informative and useful in understanding the ob_end. PHP segfaults when output buffering and sessions are enabled and a script is terminated using exit() or die() before flushing or cleaning the contents of the output buffer. my_export_file. 5. ob end will send the ouput from the script and buffer will be cleaned. This function's behaviour is controlled by the url_rewriter. Cách dùng ob start , ob flush (), flush () Trong PHP vốn đã chạy nhanh nay còn có thêm cơ chế cache làm cho ngôn ngữ PHP ngày càng hoàn hảo. They were displaying entirely to the screen and not being saved in the buffer at all. This question is in. PHP has a. Some PHP programmers put ob_start () on the first line of all of their code*, and I'm pretty certain that's what going on here. Your code might look like this: <?php ob_start (); If you say this in PHP: echo 'Hello'; it will result in the string Hello being sent to the browser more or less immediately. ob_start()とセットで使用する関数. The below code is not printing anything in the browser. If you call them from callback function, the. An array of string s. DEBUG_BACKTRACE_IGNORE_ARGS. Usually apache runs as , or apache user, depending on your configuration. ob_implicit_flush () Turns implicit flushing on or off. PHP ob_start () Function. 3. See Also ob_start() - Turn on output buffering PHP ob_start () "output buffering start → 출력 버퍼링 시작 ". Right now, it can parse the phpinfo() output when invoked from the command line, which was my use case. Điều này giúp tránh việc gửi header hoặc thiết lập cookie trước khi nội dung được xuất ra. ＋ add a note. Also look at answers to this question. If callback returns false original input is sent to the browser. The side you mention seems to refer to page load time as perceived by the user. I think you meant to use ob_end_flush instead of ob_end_clean, which sends the output buffer to the client instead of just ending buffering. ob_get_contents simply gets the contents of the output buffer since you called ob_start (). Until you end it, it will be stored in a buffer. Stack Overflow Public questions & answers; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Talent Build your employer brand Definition and Usage. First follow what the codex says Shortcodes. The ob_end_flush () function is a useful tool for flushing the output buffer and turning off output buffering in your PHP web application. The above code improve server performance as PHP will send bigger chunks of data, for example, 4KB (wihout ob_start call, php will send each echo to the browser). output_add_rewrite_var — Add URL rewriter values. And you can't redirect using the header function after you output to the page. Going by the comments of OP, I'm going to assume OP wants a timer on the command line and presume the <br> was meant to convey a newline. html). This function does not accept any parameters. 1. You will need to store the new value somewhere because multiple instances of a script do not share variables just like that. I want to be able to buffer only the contents of the tables but not the header. The output_callback parameter may be bypassed by passing a NULL value. In. Find centralized, trusted content and collaborate around the technologies you use most. ob_start (); session_start (); if. Thank you. It can conceal whitespace for HTML output. Is it possible to pause the output buffering in php so that I could skip the buffering on the table headers and resume again at the beginning of the actual content?I have a project where I am using OB_START to gather output from a PHP file. See Also. When callback is. echo "This is content inside the buffer. PHP supports single line and multi line comments. aus. The PHP function ob_start() turns on output buffering. Using the ob_get_clean() function is straightforward. Your shortcode callback is going to output content rather than return it which is why you're seeing it appear at the top of your page. It's useful in cases where you may need to filter some output, or you're using a PHP method (such as var_dump) that writes output. gzencode — Create a gzip compressed string. A common use for this is to execute something like the pbmplus utilities that can output an image. Hence, if you have any redirection calls on your page, those will. ob_start() is printing outputs without ending of ob_get_flush() 0. Next we send the header without any problem as we've not yet spit out any output. The ob_get_flush () function outputs the contents of the topmost output buffer, returns the contents and the deletes the buffer. If you want to further process the buffer's contents you have to call ob_get_contents () before ob_flush () as the buffer contents are discarded after ob_flush () is called. ob_start () starts a php feature called "output buffering" which will prevent php from directly outputting data (to the browser). 1. Used as a callback function for ob_start () to compress the contents of the buffer when sending it to the browser. 100MB. ob_start( 'ob_gzhandler', 16000, // to send data continuously PHP_OUTPUT_HANDLER_FLUSHABLE // but not removable and cleanable ); Output compression can be also activate by directive zlib. 0.