How can I capture the result of var_dump to a string?

Question

I'd like to capture the output of var_dump to a string.

The PHP documentation says;

As with anything that outputs its result directly to the browser, the output-control functions can be used to capture the output of this function, and save it in a string (for example).

What would be an example of how that might work?

print_r() isn't a valid possibility, because it's not going to give me the information that I need.

Answer 1

Try var_export

You may want to check out var_export — while it doesn't provide the same output as var_dump it does provide a second $return parameter which will cause it to return its output rather than print it:

$debug = var_export($my_var, true); 

Why?

I prefer this one-liner to using ob_start and ob_get_clean(). I also find that the output is a little easier to read, since it's just PHP code.

The difference between var_dump and var_export is that var_export returns a "parsable string representation of a variable" while var_dump simply dumps information about a variable. What this means in practice is that var_export gives you valid PHP code (but may not give you quite as much information about the variable, especially if you're working with resources).

Demo:

$demo = array(     "bool" => false,     "int" => 1,     "float" => 3.14,     "string" => "hello world",     "array" => array(),     "object" => new stdClass(),     "resource" => tmpfile(),     "null" => null, );  // var_export -- nice, one-liner $debug_export = var_export($demo, true);  // var_dump ob_start(); var_dump($demo); $debug_dump = ob_get_clean();  // print_r -- included for completeness, though not recommended $debug_printr = print_r($demo, true); 

The difference in output:

var_export ($debug_export in above example):

 array (   'bool' => false,   'int' => 1,   'float' => 3.1400000000000001,   'string' => 'hello world',   'array' =>    array (   ),   'object' =>    stdClass::__set_state(array(   )),   'resource' => NULL, // Note that this resource pointer is now NULL   'null' => NULL, ) 

var_dump ($debug_dump in above example):

 array(8) {   ["bool"]=>   bool(false)   ["int"]=>   int(1)   ["float"]=>   float(3.14)   ["string"]=>   string(11) "hello world"   ["array"]=>   array(0) {   }   ["object"]=>   object(stdClass)#1 (0) {   }   ["resource"]=>   resource(4) of type (stream)   ["null"]=>   NULL } 

print_r ($debug_printr in above example):

Array (     [bool] =>      [int] => 1     [float] => 3.14     [string] => hello world     [array] => Array         (         )      [object] => stdClass Object         (         )      [resource] => Resource id #4     [null] =>  ) 

Caveat: var_export does not handle circular references

If you're trying to dump a variable with circular references, calling var_export will result in a PHP warning:

 $circular = array();  $circular['self'] =& $circular;  var_export($circular); 

Results in:

 Warning: var_export does not handle circular references in example.php on line 3  array (    'self' =>     array (      'self' => NULL,    ),  ) 

Both var_dump and print_r, on the other hand, will output the string *RECURSION* when encountering circular references.