How to output (to a log) a multi-level array in a format that is human-readable?

I'm working on a drupal site and when debugging, I am always having to read through long, nested arrays. As a result, a large portion of my life is spent using the arrow, return, and tab keys, to split up 1000+ character strings into a nested, readable format.

For drupal devs, I can't use devel's dsm(), as I'm working with multi-step #ahah/#ajax forms, and I can only output the arrays to the error log, not to the screen.

Visual example:

Evil:

<pre>array ( 'form_wrapper' => array ( '#tree' => true, '#type' => 'fieldset', '#prefix' => '<div>', '#suffix' => '</div>', '#value' => '', 'name' => array ( '#type' => 'textfield', '#title' => NULL, '#size' => 60, '#maxlength' => 60, '#required' => false, '#description' => NULL, '#attributes' => array ( 'placeholder' => 'Email', ), '#post' => array ( 'form_wrapper' => array ( 'name' => '', 'pass' => '', ),</pre> ...

Good:

array (
'form_wrapper' => array (
'#tree' => true,
'#type' => 'fieldset',
'#prefix' => '<div>',
'#suffix' => '</div>',
'#value' => '',
'name' => array (
'#type' => 'textfield',
'#title' => NULL,
'#size' => 60,
'#maxlength' => 60,
'#required' => false,
'#description' => NULL,
'#attributes' => array (
'placeholder' => 'Email',
),

**Edit**: Sorry, by "not output to screen", I meant via drupal's system messages where it's possible to output arrays in a clickable, nested format (using devel.module).

Simple stuff:
-------------

Using `print_r`, `var_dump` or `var_export` should do it pretty nicely if you look at the result in view-source mode not in HTML mode or as @Joel Larson said if you wrap everything in a `<pre>` tag.

[`print_r`](php.net/manual/en/function.print-r.php) is best for readability but it doesn't print null/false values.

[`var_dump`](php.net/manual/en/function.var-dump.php) is best for checking types of values and lengths and null/false values.

[`var_export`](php.net/manual/en/function.var-export.php) is simmilar to `var_dump` but it can be used to get the dumped string.

The format returned by any of these is indented correctly in the source code and `var_export` can be used for logging since it can be used to return the dumped string.

Advanced stuff:
---------------

Use the xdebug plug-in for PHP this prints `var_dump`s as HTML formatted strings not as raw dump format and also allows you to supply a custom function you want to use for formatting.

<del>You should be able to use a var_dump() within a pre tag. Otherwise you could look into using a library like dump_r.php:

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;

My solution is incorrect. OP was looking for a solution formatted with spaces to store in a log file.

A solution might be to use output buffering with var_dump, then str_replace() all the tabs with spaces to format it in the log file.

Drupal's [Devel module][1] has other useful functions including ones that can print formatted arrays and objects to log files. See the guide at

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> **dd()**

> Logs any variable to a file named “drupal_debug.txt” in the
> site’s temp directory. All output from this function is appended to
> the log file, making it easy to see how the contents of a variable
> change as you modify your code.
>
> If you’re using Mac OS X you can use the Logging Console to monitor
> the contents of the log file.
>
> If you’re using a flavor of Linux you can use the command “tail -f
> drupal_debug.txt” to watch the data being logged to the file.


[1]:

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This function can be used to format output,


$output = print_r($array,1);


`$output` is a string variable, it can be logged like every other string. In pure php you can use `trigger_error`

Ex. `trigger_error($output);`

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if you need to format it also in html, you can use `<pre>` tag

This will help you

<strike>`echo '<pre>';`</strike>

$output = print_r($array,1);

<strike>`echo '</pre>';`</strike>

**EDIT**

using `echo '<pre>';` is useless, but `var_export($var);` will do the thing which you are expecting.

**Syntax**

print_r(variable, return);


variable **Required**. Specifies the variable to return information about

return **Optional**. When set to true, this function will return the information (not print it). Default is false

**Example**

error_log( print_r(<array Variable>, TRUE) );

I just wonder why nobody uses or recommends the way I prefer to debug an array:

<!-- language: lang-php -->

error_log(json_encode($array));

Next to my browser I `tail` my server log in the console eg.

<!-- language: lang-sh -->

tail -f /var/log/apache2/error.log

---

Though it's debatable if the output is human-readable, but it's still my preferred way to read it and would look something like that:

```php
[Tue Dec 13] [...] AH01071: Got error 'PHP message: {"form_wrapper":{"#tree":true,
"#type":"fieldset","#prefix":"","#suffix":"","#value":"","name":{"#type":
"textfield","#title":null,"#size":60,"#maxlength":60,"#required":false,
"#description":null,"#attributes":{"placeholder":"Email"},"#post":{
`"form_wrapper":{"name":"","pass":""}}}}}', referer:

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```

If you need to log an error to Apache error log you can try this:

error_log( print_r($multidimensionalarray, true) );

> If you would like to capture the output of [print_r()][1], use the return parameter. When this parameter is set to true, print_r() will return the information rather than print it.


[1]:

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