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这些函数的行为受 php.ini 中的设置影响。

**会话配置选项**
名字	默认	可修改范围	更新日志
session.save_path	""	PHP_INI_ALL
session.name	"PHPSESSID"	PHP_INI_ALL
session.save_handler	"files"	PHP_INI_ALL
session.auto_start	"0"	PHP_INI_PERDIR
session.gc_probability	"1"	PHP_INI_ALL
session.gc_divisor	"100"	PHP_INI_ALL	自 PHP 4.3.2 起可用。
session.gc_maxlifetime	"1440"	PHP_INI_ALL
session.serialize_handler	"php"	PHP_INI_ALL
session.cookie_lifetime	"0"	PHP_INI_ALL
session.cookie_path	"/"	PHP_INI_ALL
session.cookie_domain	""	PHP_INI_ALL
session.cookie_secure	""	PHP_INI_ALL	自 PHP 4.0.4 起有效。
session.cookie_httponly	""	PHP_INI_ALL	自 PHP 5.2.0. 有效
session.use_strict_mode	"0"	PHP_INI_ALL	自 PHP 5.5.2. 有效
session.use_cookies	"1"	PHP_INI_ALL
session.use_only_cookies	"1"	PHP_INI_ALL	自 PHP 4.3.0 起可用。
session.referer_check	""	PHP_INI_ALL
session.entropy_file	""	PHP_INI_ALL
session.entropy_length	"0"	PHP_INI_ALL
session.cache_limiter	"nocache"	PHP_INI_ALL
session.cache_expire	"180"	PHP_INI_ALL
session.use_trans_sid	"0"	PHP_INI_ALL	在 PHP <= 4.2.3 是 PHP_INI_ALL，在 PHP < 5 是 PHP_INI_PERDIR。自 PHP 4.0.3 起可用。
session.bug_compat_42	"1"	PHP_INI_ALL	自 PHP 4.3.0 起可用。
session.bug_compat_warn	"1"	PHP_INI_ALL	自 PHP 4.3.0 起可用。
session.hash_function	"0"	PHP_INI_ALL	自 PHP 5.0.0 起可用。
session.hash_bits_per_character	"4"	PHP_INI_ALL	自 PHP 5.0.0 起可用。
url_rewriter.tags	"a=href,area=href,frame=src,form=,fieldset="	PHP_INI_ALL	自 PHP 4.0.4 起可用。
session.upload_progress.enabled	"1"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.upload_progress.cleanup	"1"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.upload_progress.prefix	"upload_progress_"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.upload_progress.name	"PHP_SESSION_UPLOAD_PROGRESS"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.upload_progress.freq	"1%"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.upload_progress.min_freq	"1"	PHP_INI_PERDIR	Available since PHP 5.4.0.
session.lazy_write	"1"	PHP_INI_ALL	Available since PHP 7.0.0.

有关 PHP_INI_* 样式的更多详情与定义，见配置可被设定范围。

会话管理系统支持许多配置选项，可以在自己的 php.ini 文件中设定。这里只是个简短的概览。

session.save_handler string

session.save_handler 定义了来存储和获取与会话关联的数据的处理器的名字。默认为 files。Note that individual extensions may register their own save_handlers; registered handlers can be obtained on a per-installation basis by referring to phpinfo() . 参见 session_set_save_handler() 。

session.save_path string

session.save_path 定义了传递给存储处理器的参数。如果选择了默认的 files 文件处理器，则此值是创建文件的路径。默认为 /tmp。参见 session_save_path() 。

此指令还有一个可选的 N 参数来决定会话文件分布的目录深度。例如，设定为 '5;/tmp' 将使创建的会话文件和路径类似于 /tmp/4/b/1/e/3/sess_4b1e384ad74619bd212e236e52a5a174If。要使用 N 参数，必须在使用前先创建好这些目录。在 ext/session 目录下有个小的 shell 脚本名叫 mod_files.sh，windows 版本是 mod_files.bat 可以用来做这件事。此外注意如果使用了 N 参数并且大于 0，那么将不会执行自动垃圾回收，更多信息见 php.ini。另外如果用了 N 参数，要确保将 session.save_path 的值用双引号 "quotes" 括起来，因为分隔符分号（ ;）在 php.ini 中也是注释符号。

文件储存模块默认使用 mode 600 创建文件。通过修改可选参数 MODE 来改变这种默认行为： N;MODE;/path ，其中 MODE 是 mode 的八进制表示。 MODE 设置不影响进程的掩码(umask)。

Warning

如果将此设定为一个全局可读的目录，例如 /tmp（默认值），服务器上的其他用户有可能通过该目录的文件列表破解会话。

Caution

使用以上描述的可选目录层级参数 N 时请注意，对于绝大多数站点，大于1或者2的值会不太合适——因为这需要创建大量的目录：例如，值设置为 3 需要在文件系统上创建 64^3 个目录，将浪费很多空间和 inode。

仅仅在绝对肯定站点足够大时，才可以设置 N 大于2。

Note: 在 PHP 4.3.6 之前，Windows 用户必须修改此选项以使用 PHP 的会话函数。必须指定一个合法路径，例如：c:/temp。

session.name string

session.name 指定会话名以用做 cookie 的名字。只能由字母数字组成，默认为 PHPSESSID。参见 session_name() 。

session.auto_start boolean

session.auto_start 指定会话模块是否在请求开始时自动启动一个会话。默认为 0（不启动）。

session.serialize_handler string

session.serialize_handler 定义用来序列化／解序列化的处理器名字。当前支持 PHP 序列化格式 (名为 php_serialize)、 PHP PHP 内部格式 (名为 php 及 php_binary) 和 WDDX (名为 wddx)。如果 PHP 编译时加入了 WDDX 支持，则只能用 WDDX。自 PHP 5.5.4 起可以使用 php_serialize。 php_serialize 在内部简单地直接使用 serialize/unserialize 函数，并且不会有 php 和 php_binary 所具有的限制。使用较旧的序列化处理器导致 $_SESSION 的索引既不能是数字也不能包含特殊字符(| and !) 。使用 php_serialize 避免脚本退出时，数字及特殊字符索引导致出错。默认使用 php。

session.gc_probability integer

session.gc_probability 与 session.gc_divisor 合起来用来管理 gc（garbage collection 垃圾回收）进程启动的概率。默认为 1。详见 session.gc_divisor。

session.gc_divisor integer

session.gc_divisor 与 session.gc_probability 合起来定义了在每个会话初始化时启动 gc（garbage collection 垃圾回收）进程的概率。此概率用 gc_probability/gc_divisor 计算得来。例如 1/100 意味着在每个请求中有 1% 的概率启动 gc 进程。session.gc_divisor 默认为 100。

session.gc_maxlifetime integer

session.gc_maxlifetime 指定过了多少秒之后数据就会被视为“垃圾”并被清除。垃圾搜集可能会在 session 启动的时候开始（取决于session.gc_probability 和 session.gc_divisor）。

Note:

如果不同的脚本具有不同的 session.gc_maxlifetime 数值但是共享了同一个地方存储会话数据，则具有最小数值的脚本会清理数据。此情况下，与 session.save_path 一起使用本指令。

session.referer_check string

session.referer_check 包含有用来检查每个 HTTP Referer 的子串。如果客户端发送了 Referer 信息但是在其中并未找到该子串，则嵌入的会话 ID 会被标记为无效。默认为空字符串。

session.entropy_file string

session.entropy_file 给出了一个到外部资源（文件）的路径，该资源将在会话 ID 创建进程中被用作附加的熵值资源。例如在许多 Unix 系统下都可以用 /dev/random 或 /dev/urandom。在 Windows 上自 PHP 5.3.3 起加入了此功能。设置 session.entropy_length 为非零的值将使 PHP 使用 Windows Random API 作为熵值源。

Note: 自 PHP 5.4.0 起，默认情况下， session.entropy_file 在 /dev/urandom 或 /dev/arandom 可用的时候使用它们。在 PHP 5.3.0 中此指令默认留空。

session.entropy_length integer

session.entropy_length 指定了从上面的文件中读取的字节数。默认为 0（禁用）。

session.use_strict_mode boolean

session.use_strict_mode specifies whether the module will use strict session id mode. If this mode is enabled, the module does not accept uninitialized session ID. If uninitialized session ID is sent from browser, new session ID is sent to browser. Applications are protected from session fixation via session adoption with strict mode. Defaults to 0 (disabled).

session.use_cookies boolean

session.use_cookies 指定是否在客户端用 cookie 来存放会话 ID。默认为 1（启用）。

session.use_only_cookies boolean

session.use_only_cookies 指定是否在客户端仅仅使用 cookie 来存放会话 ID。。启用此设定可以防止有关通过 URL 传递会话 ID 的攻击。此设定是 PHP 4.3.0 添加的。自PHP 5.3.0开始，默认值改为1（启用）

session.cookie_lifetime integer

session.cookie_lifetime 以秒数指定了发送到浏览器的 cookie 的生命周期。值为 0 表示“直到关闭浏览器”。默认为 0。参见 session_get_cookie_params() 和 session_set_cookie_params() 。

Note:

The expiration timestamp is set relative to the server time, which is not necessarily the same as the time in the client's browser.

session.cookie_path string

session.cookie_path 指定了要设定会话 cookie 的路径。默认为 /。参见 session_get_cookie_params() 和 session_set_cookie_params() 。

session.cookie_domain string

session.cookie_domain 指定了要设定会话 cookie 的域名。默认为无，表示根据 cookie 规范产生 cookie 的主机名。参见 session_get_cookie_params() 和 session_set_cookie_params() 。

session.cookie_secure boolean

session.cookie_secure 指定是否仅通过安全连接发送 cookie。默认为 off。此设定是 PHP 4.0.4 添加的。参见 session_get_cookie_params() 和 session_set_cookie_params() 。

session.cookie_httponly boolean

Marks the cookie as accessible only through the HTTP protocol. This means that the cookie won't be accessible by scripting languages, such as JavaScript. This setting can effectively help to reduce identity theft through XSS attacks (although it is not supported by all browsers).

session.cache_limiter string

session.cache_limiter 指定会话页面所使用的缓冲控制方法（none/nocache/private/private_no_expire/public）。默认为 nocache。参见 session_cache_limiter() 。

session.cache_expire integer

session.cache_expire 以分钟数指定缓冲的会话页面的存活期，此设定对 nocache 缓冲控制方法无效。默认为 180。参见 session_cache_expire() 。

session.use_trans_sid boolean

session.use_trans_sid 指定是否启用透明 SID 支持。默认为 0（禁用）。

Note: 基于 URL 的会话管理比基于 cookie 的会话管理有更多安全风险。例如用户有可能通过 email 将一个包含有效的会话 ID 的 URL 发给他的朋友，或者用户总是有可能在收藏夹中存有一个包含会话 ID 的 URL 来以同样的会话 ID 去访问站点。

session.bug_compat_42 boolean

PHP 4.2.3 以及更低版本有一个未公开的特性／错误，它允许用户在 register_globals 被禁用的情况下在全局范围内初始化一个会话变量。PHP 4.3.0 及更高版本会在使用此特性时并且启用了 session.bug_compat_warn 时发出警告。此特性／错误可以通过关闭此选项而禁用。

session.bug_compat_warn boolean

PHP 4.2.3 以及更低版本有一个未公开的特性／错误，它允许用户在 register_globals 被禁用的情况下在全局范围内初始化一个会话变量。PHP 4.3.0 及更高版本会在使用此特性时并且同时启用了 session.bug_compat_42 和 session.bug_compat_warn 时发出警告。

session.hash_function mixed

session.hash_function 允许用户指定生成会话 ID 的散列算法。'0' 表示 MD5（128 位），'1' 表示 SHA-1（160 位）。

Since PHP 5.3.0 it is also possible to specify any of the algorithms provided by the hash extension (if it is available), like sha512 or whirlpool. A complete list of supported algorithms can be obtained with the hash_algos() function.

Note:

这是 PHP 5 引进的。

session.hash_bits_per_character integer

session.hash_bits_per_character 允许用户定义将二进制散列数据转换为可读的格式时每个字符存放多少个比特。可能值为 '4'（0-9，a-f），'5'（0-9，a-v），以及 '6'（0-9，a-z，A-Z，"-"，","）。

Note:

这是 PHP 5 引进的。

url_rewriter.tags string

url_rewriter.tags 指定在使用透明 SID 支持时哪些 HTML 标记会被修改以加入会话 ID。默认为 a=href,area=href,frame=src,input=src,form=fakeentry,fieldset=。

Note: 如果要符合 XHTML，去掉 form 项并在表单字段前后加上 <fieldset> 标记。

session.upload_progress.enabled boolean

Enables upload progress tracking, populating the $_SESSION variable. Defaults to 1, enabled.

session.upload_progress.cleanup boolean

Cleanup the progress information as soon as all POST data has been read (i.e. upload completed). Defaults to 1, enabled.

Note: It is highly recommended to keep this feature enabled.

session.upload_progress.prefix string

A prefix used for the upload progress key in the $_SESSION . This key will be concatenated with the value of $_POST[ini_get("session.upload_progress.name")] to provide a unique index. Defaults to "upload_progress_".

session.upload_progress.name string

The name of the key to be used in $_SESSION storing the progress information. See also session.upload_progress.prefix. If $_POST[ini_get("session.upload_progress.name")] is not passed or available, upload progressing will not be recorded. Defaults to "PHP_SESSION_UPLOAD_PROGRESS".

session.upload_progress.freq mixed

Defines how often the upload progress information should be updated. This can be defined in bytes (i.e. "update progress information after every 100 bytes"), or in percentages (i.e. "update progress information after receiving every 1% of the whole filesize"). Defaults to "1%".

session.upload_progress.min_freq integer

The minimum delay between updates, in seconds. Defaults to "1" (one second).

session.lazy_write boolean

session.lazy_write, when set to 1, means that session data is only rewritten if it changes. Defaults to 1, enabled.

register_globals 配置选项影响到会话变量是怎样存储和恢复的。

Upload progress will not be registered unless session.upload_progress.enabled is enabled, and the $_POST[ini_get("session.upload_progress.name")] variable is set. See Session Upload Progress for mor details on this functionality.

用户评论:

[#1] info at thimbleopensource dot com [2015-07-19 07:39:18]

I found out that if you need to set custom session settings, you only need to do it once when session starts. Then session maintains its settings, even if you use ini_set and change them, original session still will use it's original setting until it expires.

Just thought it might be useful to someone.

[#2] GreenReaper [2014-10-14 00:56:36]

We found a session.save_path depth of 3 led to excessive wastage of inodes and in fact disk space in storing the directory tree. dir_indexes option on ext2/3/4 makes larger directories more feasible anyway, so we decided to move to a depth of 2 instead.

It took a little puzzling to figure out how to move the existing PHP sessions up one directory tree, but we ended up running this in the root sessions directory:

#!/bin/sh
for a in .
function print_r_level($data, $level = 5)
{
    static $innerLevel = 1;

    static $tabLevel = 1;

    static $cache = array();

    $self = __FUNCTION__;

    $type       = gettype($data);
    $tabs       = str_repeat('    ', $tabLevel);
    $quoteTabes = str_repeat('    ', $tabLevel - 1);

    $recrusiveType = array('object', 'array');

    // Recrusive
    if (in_array($type, $recrusiveType))
    {
        // If type is object, try to get properties by Reflection.
        if ($type == 'object')
        {
            if (in_array($data, $cache))
            {
                return "\n{$quoteTabes}*RECURSION*\n";
            }

            // Cache the data
            $cache[] = $data;

            $output     = get_class($data) . ' ' . ucfirst($type);
            $ref        = new \ReflectionObject($data);
            $properties = $ref->getProperties();

            $elements = array();

            foreach ($properties as $property)
            {
                $property->setAccessible(true);

                $pType = $property->getName();

                if ($property->isProtected())
                {
                    $pType .= ":protected";
                }
                elseif ($property->isPrivate())
                {
                    $pType .= ":" . $property->class . ":private";
                }

                if ($property->isStatic())
                {
                    $pType .= ":static";
                }

                $elements[$pType] = $property->getValue($data);
            }
        }
        // If type is array, just retun it's value.
        elseif ($type == 'array')
        {
            $output = ucfirst($type);
            $elements = $data;
        }

        // Start dumping datas
        if ($level == 0 || $innerLevel < $level)
        {
            // Start recrusive print
            $output .= "\n{$quoteTabes}(";

            foreach ($elements as $key => $element)
            {
                $output .= "\n{$tabs}[{$key}] => ";

                // Increment level
                $tabLevel = $tabLevel + 2;
                $innerLevel++;

                $output  .= in_array(gettype($element), $recrusiveType) ? $self($element, $level) : $element;

                // Decrement level
                $tabLevel = $tabLevel - 2;
                $innerLevel--;
            }

            $output .= "\n{$quoteTabes})\n";
        }
        else
        {
            $output .= "\n{$quoteTabes}*MAX LEVEL*\n";
        }
    }

    // Clean cache
    if($innerLevel == 1)
    {
        $cache = array();
    }

    return $output;
}// End function

// TEST ------------------------------------

class testClass
{
    protected $a = 'aaa';

    private $b = 'bbb';

    public $c = array(1, 2, ['a', 'b', 'c'], 4);

    static public $d = 'ddd';

    static protected $e = 'eee';
}

$test = new testClass;

$test->testClass = $test;

echo '<pre>' . print_r_level($test, 3) . '</pre>';

?>

will output
-------------------------------------------------------------

testClass Object
(
    [a:protected] => aaa
    [b:testClass:private] => bbb
    [c] => Array
        (
            [0] => 1
            [1] => 2
            [2] => Array
                *MAX LEVEL*

            [3] => 4
        )

    [d:static] => ddd
    [e:protected:static] => eee
    [testClass] =>
        *RECURSION*

)

[#6] alex uses khimich.org [2013-10-20 21:43:27]

Sometimes, when page is called by ajax and you're not actually feeling convenient to see output of debugging, you may log it in file like shown below:

<?php // Log superglobals $g=print_r($_GET,true); $p=print_r($_POST,true); $f=print_r($_FILES,true); $s=print_r($_SESSION,true); $txt=''; $txt.="/n".'GET: '.$g; $txt.="/n".'POST: '.$p; $txt.="/n".'FILES: '.$f; $txt.="/n".'SESSION: '.$s; file_put_contents('requests.txt',$txt); ?>

[#7] bginfos at web dot de [2013-10-06 11:40:23]

function : debug_print

<?php // -------------------------------------------------------------- function debug_print($var, $nfo='DEBUG', $htm=false, $ret=false) { $var_str = print_r($var, true); if ($htm !== false) { $var_str = htmlentities($var_str); } $outstr = ''; $outstr = '<p>--------- <strong>'.$nfo.'</strong> ---------</p>'."\n"; $outstr .= '<pre style="margin:18px 4px; padding:6px; text-align:left; background:#DEDEDE; color:#000099;">'."\n"; $outstr .= $var_str."\n"; $outstr .= '</pre>'."\n"; if ($ret !== false) { $result = $outstr; } else { print $outstr; $result = true; } return $result; } // -------------------------------------------------------------- ?>

usage:

<?php // -------------------------------------------- $data = array('some', 'example', 'test'); // --- direct output --- debug_print($data); // --- returned output --- $debug_str = debug_print($data, 'some text', false, true); print $debug_str; // -------------------------------------------- ?>

[#8] preda dot vlad at yahoo dot com [2013-03-22 09:40:42]

print_r(), just like var_dump() does NOT cast an object, not even if it has a __toString() method - which is normal.

<?php
class A {
    public function __toString() {
        return 'In class A';
    }
}
$a = new A;
echo $a; // In class A
print_r($a); // A Object()
// you can simulate the echo by casting it manually
print_r((string)$a);  // In class A

[#9] ReanimationXP at g m a i l dot com [2012-07-22 12:49:15]

If you're like me and just want an exact version of print_r() except formatted to HTML without a bunch of bs, here you go.

The output is identical to print_r() but renders in HTML.

<?php // Displays a multi-dimensional array as a HTML unordered lists. function displayTree($array) { $newline = "<br>"; foreach($array as $key => $value) { //cycle through each item in the array as key => value pairs if (is_array($value) || is_object($value)) { //if the VALUE is an array, then //call it out as such, surround with brackets, and recursively call displayTree. $value = "Array()" . $newline . "(<ul>" . displayTree($value) . "</ul>)" . $newline; } //if value isn't an array, it must be a string. output its' key and value. $output .= "[$key] => " . $value . $newline; } return $output; } ?>

[#10] henzeberkheij at gmail dot com [2012-01-28 15:10:31]

print_r is used for debug purposes. Yet I had some classes where I just wanted the values coming out of the database, not all the other crap. thus i wrote the following function. If your class has an toArray function, that one will be called otherwise it will return the object as is. print_neat_classes_r is the function that should be called!

<?php print_neat_classes_r($array, $return=false){ return print_r(self::neat_class_print_r($array), $return); } function do_print_r($array, $return=false){ if(is_object($array) && method_exists($array, 'toArray')){ return $array->toArray(); }else if(is_array($array)){ foreach($array as $key=>$obj){ $array[$key] = self::do_print_r($obj, $return); } return $array; }else{ return $array; } } ?>

[#11] eithed [2011-10-21 02:25:49]

Bear in mind that print_r actually reserves some memory to do something - so, for example thing like:

<?php function shutdown_handler() { file_put_contents($_SERVER['DOCUMENT_ROOT']."/log.txt", print_r($_REQUEST, true)); } ini_set('memory_limit', '1M'); register_shutdown_function("shutdown_handler"); $array = array(); while(true) $array[] = new stdClass(); ?>

will just not work. Try using var_export, and presto, everything is fine.

[#12] jwood at JPL dot gov (w/ Bug fixed) [2011-08-10 16:04:10]

<?php // Displays a multi-dimensional array as a HTML List (Tree structure). function displayTree($var) { $newline = "\n"; foreach($var as $key => $value) { if (is_array($value) || is_object($value)) { $value = $newline . "<ul>" . displayTree($value) . "</ul>"; } if (is_array($var)) { if (!stripos($value, "<li class=")) { $output .= "<li class=\"file\">" . $value . "</li>" . $newline; } else { $output .= $value . $newline; } } else { // is_object if (!stripos($value, "<li class=")) { $value = "<ul><li class=\"file\">" . $value . "</li></ul>" . $newline; } $output .= "<li class=\"folder\">" . $key . $value . "</li>" . $newline; } } return $output; } ?>

///////////////////

Also need to add this to your style sheet (and get the necessary images...):

li.folder
{
list-style-image: url(../img/folder.gif);
}

li.file
{
list-style-image: url(../img/file.gif);
}

///////////////////

Example Usage:

<?php ... echo "<ul>"; echo displayTree($array); echo "</ul>"; ?>

[#13] Robert Heine (joomla-jquery-internet.de) [2011-04-18 07:09:55]

Since i use print_r for debugging a lot, i always use the following function in my scripts, which makes life a lot easier :-)

<?php if (!function_exists("preprint")) { function preprint($s, $return=false) { $x = "<pre>"; $x .= print_r($s, 1); $x .= "</pre>"; if ($return) return $x; else print $x; } } ?>

-------------------

USAGE: preprint($x); <- where $x = array().

-------------------

The optional 2. parameter can be set to "true", so the html-code is returned.

Have fun,

[#14] machuidel [2011-02-03 04:01:05]

The following will output an array in a PHP parsable format:

<?php function serialize_array(&$array, $root = '$root', $depth = 0) { $items = array(); foreach($array as $key => &$value) { if(is_array($value)) { serialize_array($value, $root . '[\'' . $key . '\']', $depth + 1); } else { $items[$key] = $value; } } if(count($items) > 0) { echo $root . ' = array('; $prefix = ''; foreach($items as $key => &$value) { echo $prefix . '\'' . $key . '\' => \'' . addslashes($value) . '\''; $prefix = ', '; } echo ');' . "\n"; } } ?>

[#15] Alexander [2010-03-19 05:20:36]

A simple function to send the output of print_r to firebug.
The script creates a dummy console object with a log method for when firebug is disabled/not available.

<?php function debug ($data) { echo "<script>\r\n//<![CDATA[\r\nif(!console){var console={log:function(){}}}"; $output = explode("\n", print_r($data, true)); foreach ($output as $line) { if (trim($line)) { $line = addslashes($line); echo "console.log(\"{$line}\");"; } } echo "\r\n//]]>\r\n</script>"; } ?>

[#16] liamtoh6 at hotmail dot com [2010-02-03 10:01:42]

I add this function to the global scope on just about every project I do, it makes reading the output of print_r() in a browser infinitely easier.

<?php function print_r2($val){ echo '<pre>'; print_r($val); echo '</pre>'; } ?>

It also makes sense in some cases to add an if statement to only display the output in certain scenarios, such as:

if(debug==true)
if($_SERVER['REMOTE_ADDR'] == '127.0.0.1')

[#17] jeremy dot ruten at gmail dot com [2009-09-26 19:16:03]

Here's an array_depth() function that calculates the depth of an array using the indentation in the output of print_r():

<?php function array_depth($array) { $max_indentation = 1; $array_str = print_r($array, true); $lines = explode("\n", $array_str); foreach ($lines as $line) { $indentation = (strlen($line) - strlen(ltrim($line))) / 4; if ($indentation > $max_indentation) { $max_indentation = $indentation; } } return ceil(($max_indentation - 1) / 2) + 1; } ?>

It's better than writing a recursive function to do the same thing, as print_r() handles the problem of infinitely-deep arrays for you quite nicely.

[#18] Matt [2009-09-14 12:53:03]

Here is another version that parses the print_r() output. I tried the one posted, but I had difficulties with it. I believe it has a problem with nested arrays. This handles nested arrays without issue as far as I can tell.

<?php function print_r_reverse($in) { $lines = explode("\n", trim($in)); if (trim($lines[0]) != 'Array') { // bottomed out to something that isn't an array return $in; } else { // this is an array, lets parse it if (preg_match("/(\s{5,})\(/", $lines[1], $match)) { // this is a tested array/recursive call to this function // take a set of spaces off the beginning $spaces = $match[1]; $spaces_length = strlen($spaces); $lines_total = count($lines); for ($i = 0; $i < $lines_total; $i++) { if (substr($lines[$i], 0, $spaces_length) == $spaces) { $lines[$i] = substr($lines[$i], $spaces_length); } } } array_shift($lines); // Array array_shift($lines); // ( array_pop($lines); // ) $in = implode("\n", $lines); // make sure we only match stuff with 4 preceding spaces (stuff for this array and not a nested one) preg_match_all("/^\s{4}\[(.+?)\] \=\> /m", $in, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER); $pos = array(); $previous_key = ''; $in_length = strlen($in); // store the following in $pos: // array with key = key of the parsed array's item // value = array(start position in $in, $end position in $in) foreach ($matches as $match) { $key = $match[1][0]; $start = $match[0][1] + strlen($match[0][0]); $pos[$key] = array($start, $in_length); if ($previous_key != '') $pos[$previous_key][1] = $match[0][1] - 1; $previous_key = $key; } $ret = array(); foreach ($pos as $key => $where) { // recursively see if the parsed out value is an array too $ret[$key] = print_r_reverse(substr($in, $where[0], $where[1] - $where[0])); } return $ret; } } ?>

[#19] Federico Bricker [2009-06-29 16:02:29]

Here is a nice version of print_r that prints things with colors and tables.
I've called it print_nice

<?php function print_nice($elem,$max_level=10,$print_nice_stack=array()){ if(is_array($elem) || is_object($elem)){ if(in_array(&$elem,$print_nice_stack,true)){ echo "<font color=red>RECURSION</font>"; return; } $print_nice_stack[]=&$elem; if($max_level<1){ echo "<font color=red>nivel maximo alcanzado</font>"; return; } $max_level--; echo "<table border=1 cellspacing=0 cellpadding=3 width=100%>"; if(is_array($elem)){ echo '<tr><td colspan=2 style="background-color:#333333;"><strong><font color=white>ARRAY</font></strong></td></tr>'; }else{ echo '<tr><td colspan=2 style="background-color:#333333;"><strong>'; echo '<font color=white>OBJECT Type: '.get_class($elem).'</font></strong></td></tr>'; } $color=0; foreach($elem as $k => $v){ if($max_level%2){ $rgb=($color++%2)?"#888888":"#BBBBBB"; }else{ $rgb=($color++%2)?"#8888BB":"#BBBBFF"; } echo '<tr><td valign="top" style="width:40px;background-color:'.$rgb.';">'; echo '<strong>'.$k."</strong></td><td>"; print_nice($v,$max_level,$print_nice_stack); echo "</td></tr>"; } echo "</table>"; return; } if($elem === null){ echo "<font color=green>NULL</font>"; }elseif($elem === 0){ echo "0"; }elseif($elem === true){ echo "<font color=green>TRUE</font>"; }elseif($elem === false){ echo "<font color=green>FALSE</font>"; }elseif($elem === ""){ echo "<font color=green>EMPTY STRING</font>"; }else{ echo str_replace("\n","<strong><font color=red>*</font></strong><br>\n",$elem); } } ?>

[#20] Bob [2009-05-08 03:19:02]

Here is a function that formats the output of print_r as a expandable/collapsable tree list using HTML and JavaScript.
<?php function print_r_tree($data) { // capture the output of print_r $out = print_r($data, true); // replace something like '[element] => <newline> (' with <a href="javascript:toggleDisplay('...');">...</a><div id="..." style="display: none;"> $out = preg_replace('/([ \t]*)(\[[^\]]+\][ \t]*\=\>[ \t]*[a-z0-9 \t_]+)\n[ \t]*$/iUe',"'\\1<a href=\"javascript:toggleDisplay(\''.(\$id = substr(md5(rand().'\\0'), 0, 7)).'\');\">\\2</a><div id=\"'.\$id.'\" style=\"display: none;\">'", $out); // replace ')' on its own on a new line (surrounded by whitespace is ok) with '</div> $out = preg_replace('/^\s*$\s*$/m', '</div>', $out); // print the javascript function toggleDisplay() and then the transformed output echo '<script language="Javascript">function toggleDisplay(id) { document.getElementById(id).style.display = (document.getElementById(id).style.display == "block") ? "none" : "block"; }</script>'."\n$out"; } ?>
Pass it a multidimensional array or object and each sub-array/object will be hidden and replaced by a html link that will toggle its display on and off.
Its quick and dirty, but great for debugging the contents of large arrays and objects.
Note: You'll want to surround the output with <pre></pre>

[#21] sebasg37 at gmail dot com [2009-01-25 21:35:58]

If you have to catch the output without showing it at all at first (for example, if you want to append the print_r output to a file), you can do this:

<?php ob_start(); print_r( $some_array ); $output = ob_get_clean(); // if you want to append the print_r output of $some_array to, let's say, log.txt: file_put_contents( 'log.txt', file_get_contents( 'log.txt' ) . $output ) ?>

[#22] afisher8 at cox dot net [2008-12-17 08:53:47]

I use this all the time when debugging objects, but when you have a very large object with big arrays of sub-objects, it's easy to get overwhelmed with the large amount of output....sometimes you don't want to see absolutely every sub-object.

I made this function to debug objects while "hiding" sub-objects of certain types. This also color codes the output for a more readable printout.

<?php function wtf($var, $arrayOfObjectsToHide=null, $fontSize=11) { $text = print_r($var, true); if (is_array($arrayOfObjectsToHide)) { foreach ($arrayOfObjectsToHide as $objectName) { $searchPattern = '#('.$objectName.' Object\n(\s+)$).*?\n\2$\n#s'; $replace = "$1<span style=\"color: #FF9900;\">--> HIDDEN - courtesy of wtf() <--</span>)"; $text = preg_replace($searchPattern, $replace, $text); } } // color code objects $text = preg_replace('#(\w+)(\s+Object\s+\()#s', '<span style="color: #079700;">$1</span>$2', $text); // color code object properties $text = preg_replace('#\[(\w+)\:(public|private|protected)\]#', '[<span style="color: #000099;">$1</span>:<span style="color: #009999;">$2</span>]', $text); echo '<pre style="font-size: '.$fontSize.'px; line-height: '.$fontSize.'px;">'.$text.'</pre>'; } // example usage: wtf($myBigObject, array('NameOfObjectToHide_1', 'NameOfObjectToHide_2')); ?>

[#23] vista_ at live dot se [2008-12-04 08:31:42]

Do you think it is difficult to see what print_r() returns?

<?php echo '<pre>'; print_r($array); echo '</pre>'; ?>

And if you have to write this many times in a page, use this:

<?php function preint_r($array) { echo '<pre>'; print_r($array); echo '</pre>'; } ?>

[#24] kurt krueckeberg [2008-10-28 10:53:19]

This is an alternative for printing arrays. It bolds array values.

<?php function print_array(&$a, $str = "") { if ($str[0]) { echo "$str ="; } echo ' array( '; foreach ($a as $k => $v) { echo "[$k]".' => '; if (is_array($v)) { print_array($v); } else { echo "<strong>$a[$k]</strong> "; } } echo ') '; } $a1 = array ("apples", "oranges", "pears"); $a2 = array ("potatos", "green beans", "squash"); $a3 = array ("euros", "dollars", "pesos", "dinars"); $test = range(1, 9); array_push($test, array ("fruit" => $a1, "vegies" => $a2, "money" => $a3)); print_array($test, "test"); ?>

[#25] schizo do not spamme duckie at gmail dot com [2008-10-07 05:00:13]

my take on the highlighted markupped debug function:

<?php function print_array($var) { $input =var_export($var,true); $input = preg_replace("! => \n\W+ array $!Uims", " => Array ( ", $input); $input = preg_replace("!array \(\W+$,!Uims", "Array ( ),", $input); return("<pre>".str_replace('><?', '>', highlight_string('<'.'?'.$input, true))."</pre>"); } ?>

[#26] brenden at beagleproductions dot com [2008-08-28 13:58:03]

Many developers have submitted bugs to the PHP development team with regards to print_r showing protected and private properties of objects (PHP 5). This is not a bug; sensitive information (ex. database connection object) should be encapsulated within a private member function of your class.

[#27] admin at swivelgames dot com [2008-08-17 13:44:23]

I was having problems using print_r because I didn't like the fact that if tags where included in the array it would still be parsed by the browsers.

Heres a simple fix for anyone who is having the same problem as I did. This will output your text properly for viewing through the browser instead of the browser's "view source" or CLI.

Script:
<?php $MyArray[0]="<div align='center'>My Text</div>"; echo "<pre>".htmlspecialchars(print_r($MyArray,true))."</pre>"; ?>

Output:
<pre>Array
(
[0] => <div align='center'>My Text</div>
)
</pre>

[#28] Anonymous [2008-06-28 13:21:52]

I have written a nice debugging function.
This function handles arrays beautifully.
<?php //Debug variables, $i and $k are for recursive use function DebugDisplayVar($input, $name = "Debug", $i = "0", $k = array("Error")){ if(is_array($input)) { foreach ($input as $i => $value){ $temp = $k; $temp[] = $i; DebugDisplayVar($value, $name, $i, $temp);} }else{//if not array echo "$".$name;//[$k] foreach ($k as $i => $value){ if($value !=="Error"){echo "[$value]";} } echo " = $input<br>"; } } //outputs Debug[0] = value Debug[1] = another value ect... ?>

[#29] janci [2008-05-13 02:49:32]

You cannot use print_r(), var_dump() nor var_export() to get static member variables of a class. However, in PHP5 you can use Reflection classes for this:

<?php $reflection = new ReflectionClass('Static'); print_r($reflection->getStaticProperties()); ?>

[#30] tylmann at corvent dot ch [2008-03-28 02:07:19]

There is a library to create nice output of variables, arrays, hash-tables and even objects. It is great for developing/debugging and looks very much better than any print_r output.

Usage:
<?php debug::show($myVar, 'caption'); ?>

You can download it for free at http://sourceforge.net/projects/phpcorestdfuncs

For an example take a look at http://demo.corvent.ch/stdfuncs/

[#31] helpful at maybe dot com [2008-03-06 20:13:41]

Another slight modification to the previous post to allow for empty array elements

added the following lines after the first preg_match block
<?php } else if ($expecting == 2 && preg_match('/^\[(.+?)\] \=\>$/', $trim, $matches)) { // array element // the array element is blank list ($fullMatch, $key) = $matches; $topArray[$key] = $element; } ?>

[#32] anon at anon dot com [2008-02-29 10:30:33]

A slight modification to the previous post to allow for arrays containing mutli line strings. haven't fully tested it with everything, but seems to work great for the stuff i've done so far.

<?php function print_r_reverse(&$output) {     $expecting = 0; // 0=nothing in particular, 1=array open paren '(', 2=array element or close paren ')'     $lines = explode("\n", $output);     $result = null;     $topArray = null;     $arrayStack = array();     $matches = null;     while (!empty($lines) && $result === null)     {         $line = array_shift($lines);         $trim = trim($line);         if ($trim == 'Array')         {             if ($expecting == 0)             {                 $topArray = array();                 $expecting = 1;             }             else             {                 trigger_error("Unknown array.");             }         }         else if ($expecting == 1 && $trim == '(')         {             $expecting = 2;         }         else if ($expecting == 2 && preg_match('/^\[(.+?)\] \=\> (.+)$/', $trim, $matches)) // array element         {             list ($fullMatch, $key, $element) = $matches;             if (trim($element) == 'Array')             {                 $topArray[$key] = array();                 $newTopArray =& $topArray[$key];                 $arrayStack[] =& $topArray;                 $topArray =& $newTopArray;                 $expecting = 1;             }             else             {                 $topArray[$key] = $element;             }         }         else if ($expecting == 2 && $trim == ')') // end current array         {             if (empty($arrayStack))             {                 $result = $topArray;             }             else // pop into parent array             {                 // safe array pop                 $keys = array_keys($arrayStack);                 $lastKey = array_pop($keys);                 $temp =& $arrayStack[$lastKey];                 unset($arrayStack[$lastKey]);                 $topArray =& $temp;             }         }         // Added this to allow for multi line strings.     else if (!empty($trim) && $expecting == 2)     {         // Expecting close parent or element, but got just a string         $topArray[$key] .= "\n".$line;     }         else if (!empty($trim))         {             $result = $line;         }     }         $output = implode(n, $lines);     return $result; } function print_r_reverse_multiple($output) {     $result = array();     while (($reverse = print_r_reverse($output)) !== NULL)     {         $result[] = $reverse;     }     return $result; } $output = ' Array (     [a] => apple     [b] => banana     [c] => Array         (             [0] => x             [1] => y             [2] => z             [3] => Array             (                 [nest] => yes                 [nest2] => Array                 (                     [nest] => some more                     asffjaskkd                 )                 [nest3] => o rly?             )         ) ) some extra stuff '; var_dump(print_r_reverse($output), $output); ?>

This should output

array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  array(4) {
    [0]=>
    string(1) "x"
    [1]=>
    string(1) "y"
    [2]=>
    string(1) "z"
    [3]=>
    array(3) {
      ["nest"]=>
      string(3) "yes"
      ["nest2"]=>
      array(1) {
        ["nest"]=>
        string(40) "some more
                    asffjaskkd"
      }
      ["nest3"]=>
      string(6) "o rly?"
    }
  }
}
string(18) "nsome extra stuffn"

Added:
else if (!empty($trim) && $expecting == 2)
{
// Expecting close parent or element, but got just a string
$topArray[$key] .= "\n".$line;
}

[#33] ario at mail dot utexas dot [education - 3 letters] [2008-02-19 12:34:51]

This is a better print_r reverse algorithm, that works with arbitrary nested arrays.  Anything else it treats as strings.  The second function allows you to take a string with multiple print_r results concatenated, and returns the result of parsing each of them.

<?php function print_r_reverse(&$output) {     $expecting = 0; // 0=nothing in particular, 1=array open paren '(', 2=array element or close paren ')'     $lines = explode("\n", $output);     $result = null;     $topArray = null;     $arrayStack = array();     $matches = null;     while (!empty($lines) && $result === null)     {         $line = array_shift($lines);         $trim = trim($line);         if ($trim == 'Array')         {             if ($expecting == 0)             {                 $topArray = array();                 $expecting = 1;             }             else             {                 trigger_error("Unknown array.");             }         }         else if ($expecting == 1 && $trim == '(')         {             $expecting = 2;         }         else if ($expecting == 2 && preg_match('/^\[(.+?)\] \=\> (.+)$/', $trim, $matches)) // array element         {             list ($fullMatch, $key, $element) = $matches;             if (trim($element) == 'Array')             {                 $topArray[$key] = array();                 $newTopArray =& $topArray[$key];                 $arrayStack[] =& $topArray;                 $topArray =& $newTopArray;                 $expecting = 1;             }             else             {                 $topArray[$key] = $element;             }         }         else if ($expecting == 2 && $trim == ')') // end current array         {             if (empty($arrayStack))             {                 $result = $topArray;             }             else // pop into parent array             {                 // safe array pop                 $keys = array_keys($arrayStack);                 $lastKey = array_pop($keys);                 $temp =& $arrayStack[$lastKey];                 unset($arrayStack[$lastKey]);                 $topArray =& $temp;             }         }         else if (!empty($trim))         {             $result = $line;         }     }          $output = implode(n, $lines);     return $result; } function print_r_reverse_multiple($output) {     $result = array();     while (($reverse = print_r_reverse($output)) !== NULL)     {         $result[] = $reverse;     }     return $result; } $output = ' Array (     [a] => apple     [b] => banana     [c] => Array         (             [0] => x             [1] => y             [2] => z             [3] => Array             (                 [nest] => yes                 [nest2] => Array                 (                     [nest] => some more                 )                 [nest3] => o rly?             )         ) ) some extra stuff '; var_dump(print_r_reverse($output), $output); ?>

The above example will output:

array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["c"]=>
  array(4) {
    [0]=>
    string(1) "x"
    [1]=>
    string(1) "y"
    [2]=>
    string(1) "z"
    [3]=>
    array(3) {
      ["nest"]=>
      string(3) "yes"
      ["nest2"]=>
      array(1) {
        ["nest"]=>
        string(9) "some more"
      }
      ["nest3"]=>
      string(6) "o rly?"
    }
  }
}
string(20) "
some extra stuff
"

[#34] Kokos [2008-01-31 04:52:55]

A simple function that will output an array more easily to read than print_r();

<?php function echo_array($array,$return_me=false){ if(is_array($array) == false){ $return = "The provided variable is not an array."; }else{ foreach($array as $name=>$value){ if(is_array($value)){ $return .= ""; $return .= "['<b>$name</b>'] {<div style='margin-left:10px;'>\n"; $return .= echo_array($value,true); $return .= "</div>}"; $return .= "\n\n"; }else{ if(is_string($value)){ $value = "\"$value\""; } $return .= "['<b>$name</b>'] = $value\n\n"; } } } if($return_me == true){ return $return; }else{ echo "<pre>".$return."</pre>"; } } ?>

[#35] bart at mediawave dot nl [2007-10-30 16:27:05]

Here's a PHP version of print_r which can be tailored to your needs. Shows protected and private properties of objects and detects recursion (for objects only!). Usage:

void u_print_r ( mixed $expression [, array $ignore] )

Use the $ignore parameter to provide an array of property names that shouldn't be followed recursively.

<?php function u_print_r($subject, $ignore = array(), $depth = 1, $refChain = array()) {     if ($depth > 20) return;     if (is_object($subject)) {         foreach ($refChain as $refVal)             if ($refVal === $subject) {                 echo "*RECURSION*\n";                 return;             }         array_push($refChain, $subject);         echo get_class($subject) . " Object ( \n";         $subject = (array) $subject;         foreach ($subject as $key => $val)             if (is_array($ignore) && !in_array($key, $ignore, 1)) {                 echo str_repeat(" ", $depth * 4) . '[';                 if ($key{0} == "\0") {                     $keyParts = explode("\0", $key);                     echo $keyParts[2] . (($keyParts[1] == '*')  ? ':protected' : ':private');                 } else                     echo $key;                 echo '] => ';                 u_print_r($val, $ignore, $depth + 1, $refChain);             }         echo str_repeat(" ", ($depth - 1) * 4) . ")\n";         array_pop($refChain);     } elseif (is_array($subject)) {         echo "Array ( \n";         foreach ($subject as $key => $val)             if (is_array($ignore) && !in_array($key, $ignore, 1)) {                 echo str_repeat(" ", $depth * 4) . '[' . $key . '] => ';                 u_print_r($val, $ignore, $depth + 1, $refChain);             }         echo str_repeat(" ", ($depth - 1) * 4) . ")\n";     } else         echo $subject . "\n"; } ?>

Example:

<?php class test {     public $var1 = 'a';     protected $var2 = 'b';     private $var3 = 'c';     protected $array = array('x', 'y', 'z'); } $test = new test(); $test->recursiveRef = $test; $test->anotherRecursiveRef->recursiveRef = $test; $test->dont->follow = 'me'; u_print_r($test, array('dont')); ?>

Will produce:

test Object (
    [var1] => a
    [var2:protected] => b
    [var3:private] => c
    [array:protected] => Array (
        [0] => x
        [1] => y
        [2] => z
    )
    [recursiveRef] => *RECURSION*
    [anotherRecursiveRef] => stdClass Object (
        [recursiveRef] => *RECURSION*
    )
)

[#36] php at deboom dot biz [2007-09-21 05:17:33]

If you need to import an print_R output back to an array you could use this.

This could also be (ab)used to convert a object into a array...

<?php function object2array($printr) { $newarray = array(); $a[0] = &$newarray; if (preg_match_all('/^\s+\[(\w+).*\] => (.*)\n/m', $printr, $match)) { foreach ($match[0] as $key => $value) { (int)$tabs = substr_count(substr($value, 0, strpos($value, "[")), " "); if ($match[2][$key] == 'Array' || substr($match[2][$key], -6) == 'Object') { $a[$tabs+1] = &$a[$tabs][$match[1][$key]]; } else { $a[$tabs][$match[1][$key]] = $match[2][$key]; } } } return $newarray; } ?>

[#37] motin at demomusic dot nu [2007-06-19 16:01:09]

This works around the hacky nature of print_r in return mode (using output buffering for the return mode to work is hacky...):

<?php function obsafe_print_r($var, $return = false, $html = false, $level = 0) { $spaces = ""; $space = $html ? " " : " "; $newline = $html ? "<br />" : "\n"; for ($i = 1; $i <= 6; $i++) { $spaces .= $space; } $tabs = $spaces; for ($i = 1; $i <= $level; $i++) { $tabs .= $spaces; } if (is_array($var)) { $title = "Array"; } elseif (is_object($var)) { $title = get_class($var)." Object"; } $output = $title . $newline . $newline; foreach($var as $key => $value) { if (is_array($value) || is_object($value)) { $level++; $value = obsafe_print_r($value, true, $html, $level); $level--; } $output .= $tabs . "[" . $key . "] => " . $value . $newline; } if ($return) return $output; else echo $output; } ?>

Built on a function earlier posted in these comments as stated in the Doc comment. Cheers! /Fredrik (Motin)

[#38] mrasnika at users dot sourceforge dot net [2007-04-26 11:30:39]

We can all agree that print_r() output is very spartan looking. The debug data needs to be organized better, and presented in a graceful way. In the era of Web 2.0 it is somewhat strange to use plain text to dump information. A DHTML powered informatiion dumping tool will be quite better - like the the open-source alternative of print_r(); -- Krumo (http://krumo.sourceforge.net).

It renders the output using DHTML and collapsible nodes, it's layout is "skinable" and you can change it to fit your aesthetic taste. Krumo makes the output "human-readable" for real :) Plus it is compliant with both PHP4 and PHP5. Plus it detects "reference recursion". Plus you can use it to dump all various sort of data like debug back-traces, the superglobals ($_SERVER, $_ENV, $_REQUEST, $_COOKIE, $_GET, $_POST, $_SESSION), all the included files, all the declared classes, all the declared constants, all your PHP settings, all your php.ini values (if it is readable), all the loaded extensions, all the HTTP request headers, all the declared interfaces (for PHP5), all the file paths from INCLUDE_PATH, all the values of any particular INI file. Additionally it is designed to be easy to use - for example you can disable all the Krumo dumps instead of cleaning your code out of all print_r()'s and var_dump()'s. Anyway, if you check the site (http://krumo.sourceforge.net), you can found a lot of examples, demonstrations, documentation and all sort of helpful information.

[#39] Enthusiastic PHPers [2007-03-22 12:03:44]

We had an interesting problem dumping an object that
contained embedded HTML. The application makes use
of buffer manipulation functions, so print_r's 2nd argument
wasn't helpful. Here is how we solved the problem:

$object = new ObjectContainingHTML();
$savedbuffercontents = ob_get_clean();
print_r($object);
$print_r_output = ob_get_clean();
ob_start();
echo $savedbuffercontents;
echo htmlentities($print_r_output);

[#40] Matthew Ruivo (mruivo at gmail) [2007-02-22 22:47:40]

For those of you needing to print an array within a buffer callback function, I've created this quick function. It simply returns the array as a readable string rather than printing it. You can even choose whether to return it in normal text-mode or HTML. It's recursive, so multi-dimensial arrays are supported. I hope someone finds this useful!

<?php function return_array($array, $html = false, $level = 0) { $space = $html ? " " : " "; $newline = $html ? "<br />" : "\n"; for ($i = 1; $i <= 6; $i++) { $spaces .= $space; } $tabs = $spaces; for ($i = 1; $i <= $level; $i++) { $tabs .= $spaces; } $output = "Array" . $newline . $newline; foreach($array as $key => $value) { if (is_array($value)) { $level++; $value = return_array($value, $html, $level); $level--; } $output .= $tabs . "[" . $key . "] => " . $value . $newline; } return $output; } ?>

[#41] markus (at) maxxmaster (dot) org [2007-01-17 06:11:19]

i've been using a similar idea like Sawey's for quite a long time,
but was always disappointed that you don't see the name of the
variable passed to the function (eg calling it many times, you don't
know which value was provided by a certain variable at a certain time).
so i combined sawey's idea with one found on php.net to solve that problem.
for shellscripting the function only uses <pre>-tags when called in the web.

<?php function my_r(&$var, $scope=false, $label=false){ if (is_string($scope) && $label==false) $label=$scope; if (!is_array($scope)) $scope = &$GLOBALS; $origin = $var; $var = $checker = "very_weird_value#".rand()."#isnt_it"; $vname = false; foreach ($scope as $key => $value){ if ($value === $checker){ $vname = "\$".$key; } if (is_array($value) && $key!="GLOBALS"){ if ($pfad=aver($var,$value)){ $vname = "\$${key}[\"". implode("\"][\"",$pfad)."\"]"; } } if (is_object($value)){ if ($pfad=aver($var,get_object_vars($value))){ if (sizeof($pfad)<2) $vname = "\$${key}->".$pfad[0]; else{ $vname ="\$${key}->".$pfad[0]; $vname.="[\"".implode("\"][\"", array_slice($pfad,1))."\"]"; } } } if ($vname) break; } $var = $origin; if ($_SERVER["SERVER_NAME"] && !isset($_SERVER["TERM"])) echo "<pre>"; if ($vname){ echo $vname; if ($label) echo " #" . $label . "# "; else echo ": "; }else{ if ($label) echo "$label: "; } print_r($var); if ($_SERVER["SERVER_NAME"] && !isset($_SERVER["TERM"])) echo "</pre>"; } function aver($needle,$haystack) { // array value exists recursive foreach($haystack as $key=>$val) { if(is_array($val) && $needle != $val && $key != "GLOBALS") { if($foo=aver($needle,$val)) return array_merge(array($key),$foo); }elseif($val === $needle) return array($key); } return false; } ?>

[#42] SaWey @ localdomain [2007-01-15 11:44:46]

I've seen a lot of tries to give an easy way to output the "print_r" info in a decent way in you favorite browser.

Here's mine:

echo ("<pre>");
print_r("-->here goes your data to output<--");
echo ("<pre>");

I personaly think this is the easyest way.
Grz

[#43] Dmitry Kochin <dco at mail dot ru> [2006-09-08 01:20:12]

Sometimes print_r produces large output, especially when the data hierarchy is too deep. It is very difficult to analyze the dump about 1Mb length.

It would be great to have some way to fold arrays and objects and to look deeper into hierarchy only on demand.

Here is the solution. Just pass the print_r output to debug_var function:

debug_var('title', print_r($var, true));

and it will produce nice html with folding option.

<?php   ob_start(); ?>
Locals: Array
(
    [arr] => Array
        (
            [0] => Bon Object
                (
                    [n] => id
                    [v] => 1
                    [dv] =>
                    [dn] =>
                )

        )

    [b] => Bon Object
        (
            [n] => id
            [v] => 1
            [dv] =>
            [dn] =>
        )

    [k] => 0
    [row] => Array
        (
            [aid] => 1
            [bonus] => spell.id: 125;
            [req] =>
            [brcache] =>
            [auto] => 0
        )

    [sp] =>
)
<?php   $str = ob_get_contents();   ob_end_clean();   debug_var('locals', $str); function debug_var($name,$data) {     $captured = preg_split("/\r?\n/",$data);     print "<script>function toggleDiv(num){       var span = document.getElementById('d'+num);       var a = document.getElementById('a'+num);       var cur = span.style.display;       if(cur == 'none'){         a.innerHTML = '-';         span.style.display = 'inline';       }else{         a.innerHTML = '+';         span.style.display = 'none';       }     }</script>";     print "<b>$name</b>\n";     print "<pre>\n";     foreach($captured as $line)     {         print debug_colorize_string($line)."\n";     }     print "</pre>\n"; } function next_div($matches) {   static $num = 0;   ++$num;   return "$matches[1]<a id=a$num href=\"javascript: toggleDiv($num)\">+</a><span id=d$num style=\"display:none\">("; } function debug_colorize_string($string) {     $string = preg_replace("/\[(\w*)\]/i", '[<font color="red">$1</font>]', $string);     $string = preg_replace_callback("/(\s+)$$/", 'next_div', $string);     $string = preg_replace("/(\s+)$$/", '$1)</span>', $string);                 $string = str_replace('Array','<font color="blue">Array</font>',$string);           $string = str_replace('=>','<font color="#556F55">=></font>',$string);     return $string; } ?>

This example uses ideas from this article:
http://www.zend.com/zend/tut/tutorial-DebugLib.php

[#44] ohira (atto) web. de [2006-04-13 07:01:05]

Bases on thbley?s sript i use this one to log some actions.
It will return a tabbed like string which you can output or whatever.

Input fields like "Password" will not be shown.

<?php function print_r_string($arr,$first=true,$tab=0) { $output = ""; $tabsign = ($tab) ? str_repeat('    ',$tab) : ''; if ($first) $output .= "<pre><br>\n"; foreach($arr as $key => $val) { switch (gettype($val)) { case "array": $output .= $tabsign."[".htmlspecialchars($key)."] = array(".count($val).")<br>\n".$tabsign."(<br>\n"; $tab++; $output .= print_r_string($val,false,$tab); $tab--; $output .= $tabsign.")<br>\n"; break; case "boolean": $output .= $tabsign."[".htmlspecialchars($key)."] bool = '".($val?"true":"false")."'<br>\n"; break; case "integer": $output .= $tabsign."[".htmlspecialchars($key)."] int = '".htmlspecialchars($val)."'<br>\n"; break; case "double": $output .= $tabsign."[".htmlspecialchars($key)."] double = '".htmlspecialchars($val)."'<br>\n"; break; case "string": $output .= $tabsign."[".htmlspecialchars($key)."] string = '".((stristr($key,'passw')) ? str_repeat('*', strlen($val)) : htmlspecialchars($val))."'<br>\n"; break; default: $output .= $tabsign."[".htmlspecialchars($key)."] unknown = '".htmlspecialchars(gettype($val))."'<br>\n"; break; } } if ($first) $output .= "</pre><br>\n"; return $output; } echo print_r_string(array($_POST,$_GET)); // for Example ?>

[#45] reinder at fake-address dot com [2006-01-31 09:09:36]

I always use this function in my code, because most of my functions return an Array or Boolean :

<?php function printr ( $object , $name = '' ) { print ( '\'' . $name . '\' : ' ) ; if ( is_array ( $object ) ) { print ( '<pre>' ) ; print_r ( $object ) ; print ( '</pre>' ) ; } else { var_dump ( $object ) ; } } ?>

( print_r gives no output on FALSE and that can be annoying! )

[#46] thbley at gmail dot com [2005-11-16 12:10:24]

Here is a print_r that produces xml:
(now you can expand/collapse the nodes in your browser)

<?php header('Content-Type: text/xml; charset=UTF-8'); echo print_r_xml($some_var); function print_r_xml($arr,$first=true) {   $output = "";   if ($first) $output .= "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<data>\n";
  foreach($arr as $key => $val) {
    if (is_numeric($key)) $key = "arr_".$key; // <0 is not allowed
    switch (gettype($val)) {
  case "array":
        $output .= "<".htmlspecialchars($key)." type='array' size='".count($val)."'>".
  print_r_xml($val,false)."</".htmlspecialchars($key).">\n"; break;
      case "boolean":
        $output .= "<".htmlspecialchars($key)." type='bool'>".($val?"true":"false").
  "</".htmlspecialchars($key).">\n"; break;
      case "integer":
        $output .= "<".htmlspecialchars($key)." type='integer'>".
  htmlspecialchars($val)."</".htmlspecialchars($key).">\n"; break;
      case "double":
        $output .= "<".htmlspecialchars($key)." type='double'>".
  htmlspecialchars($val)."</".htmlspecialchars($key).">\n"; break;
      case "string":
        $output .= "<".htmlspecialchars($key)." type='string' size='".strlen($val)."'>".
  htmlspecialchars($val)."</".htmlspecialchars($key).">\n"; break;
      default:
        $output .= "<".htmlspecialchars($key)." type='unknown'>".gettype($val).
  "</".htmlspecialchars($key).">\n"; break;
    }
  }
  if ($first) $output .= "</data>\n";
  return $output;
}

?>

[#47] warhog at warhog dot net [2005-08-11 17:01:13]

For very long arrays I have written a little function which formats an array quite nice and uses javascript for browsing it like a tree. The function is very customizable with the $style parameter.
For me it's of great use for browsing large array's, for example when those are used in language-files in some script and so on. It may even be used in "real" scripts for the "real" front-end, cause the tree can very easily be styled (look at the function or the outputted source and you'll see what i mean).

Here's the function:

<?php function print_r_html($arr, $style = "display: none; margin-left: 10px;") { static $i = 0; $i++; echo "\n<div id=\"array_tree_$i\" class=\"array_tree\">\n"; foreach($arr as $key => $val) { switch (gettype($val)) { case "array": echo "<a onclick=\"document.getElementById('"; echo array_tree_element_$i."').style.display = "; echo "document.getElementById('array_tree_element_$i"; echo "').style.display == 'block' ?"; echo "'none' : 'block';\"\n"; echo "name=\"array_tree_link_$i\" href=\"#array_tree_link_$i\">".htmlspecialchars($key)."</a><br />\n"; echo "<div class=\"array_tree_element_\" id=\"array_tree_element_$i\" style=\"$style\">"; echo print_r_html($val); echo "</div>"; break; case "integer": echo "<b>".htmlspecialchars($key)."</b> => <i>".htmlspecialchars($val)."</i><br />"; break; case "double": echo "<b>".htmlspecialchars($key)."</b> => <i>".htmlspecialchars($val)."</i><br />"; break; case "boolean": echo "<b>".htmlspecialchars($key)."</b> => "; if ($val) { echo "true"; } else { echo "false"; } echo "<br />\n"; break; case "string": echo "<b>".htmlspecialchars($key)."</b> => <code>".htmlspecialchars($val)."</code><br />"; break; default: echo "<b>".htmlspecialchars($key)."</b> => ".gettype($val)."<br />"; break; } echo "\n"; } echo "</div>\n"; } ?>

The function as it is now does not support the $return parameter as print_r does and will create an endless loop like print_r did in php-versions < 4.0.3 when there is an element which contains a reference to a variable inside of the array to print out :-/

I've tested it with PHP 5.0.6 and PHP 4.2.3 - no problems except those already mentioned.

please e-mail me if you've got a solution for the problems i've mentioned, i myself are not able to solve them 'cause i don't know how the hell i can find out whether a variable is a reference or not.

[#48] nicky dot weber at siner dot de [2005-06-11 02:13:18]

Print arrays formatted for a browser easily:

<?php function print_html_r( $aData ) { echo nl2br( eregi_replace( " ", " ", print_r( $data, TRUE ) ) ); } ?>

[#49] general at NOSPAMbugfoo dot com [2005-01-20 13:23:18]

You can't use print_r($var, TRUE) inside a function which is a callback from ob_start() or you get the following error:
Fatal error: print_r(): Cannot use output buffering in output buffering display handlers