Output Class

The Output class is a core class with one main function: To send the finalized web page to the requesting browser. It is also responsible for caching your web pages, if you use that feature.


This class is initialized automatically by the system so there is no need to do it manually.

Under normal circumstances you won’t even notice the Output class since it works transparently without your intervention. For example, when you use the Loader class to load a view file, it’s automatically passed to the Output class, which will be called automatically by CodeIgniter at the end of system execution. It is possible, however, for you to manually intervene with the output if you need to.

Class Reference

class CI_Output
$parse_exec_vars = TRUE;

Enables/disables parsing of the {elapsed_time} and {memory_usage} pseudo-variables.

CodeIgniter will parse those tokens in your output by default. To disable this, set this property to FALSE in your controller.

$this->output->parse_exec_vars = FALSE;
Parameters:$output (string) – String to set the output to
Returns:CI_Output instance (method chaining)
Return type:CI_Output

Permits you to manually set the final output string. Usage example:



If you do set your output manually, it must be the last thing done in the function you call it from. For example, if you build a page in one of your controller methods, don’t set the output until the end.

set_content_type($mime_type[, $charset = NULL])
  • $mime_type (string) – MIME Type idenitifer string
  • $charset (string) – Character set

CI_Output instance (method chaining)

Return type:


Permits you to set the mime-type of your page so you can serve JSON data, JPEG’s, XML, etc easily.

        ->set_output(json_encode(array('foo' => 'bar')));

        ->set_content_type('jpeg') // You could also use ".jpeg" which will have the full stop removed before looking in config/mimes.php


Make sure any non-mime string you pass to this method exists in application/config/mimes.php or it will have no effect.

You can also set the character set of the document, by passing a second argument:

$this->output->set_content_type('css', 'utf-8');
Returns:Content-Type string
Return type:string

Returns the Content-Type HTTP header that’s currently in use, excluding the character set value.

$mime = $this->output->get_content_type();


If not set, the default return value is ‘text/html’.

Parameters:$header (string) – HTTP header name
Returns:HTTP response header or NULL if not found
Return type:mixed

Returns the requested HTTP header value, or NULL if the requested header is not set. Example:

$this->output->set_content_type('text/plain', 'UTF-8');
echo $this->output->get_header('content-type');
// Outputs: text/plain; charset=utf-8


The header name is compared in a case-insensitive manner.


Raw headers sent via PHP’s native header() function are also detected.

Returns:Output string
Return type:string

Permits you to manually retrieve any output that has been sent for storage in the output class. Usage example:

$string = $this->output->get_output();

Note that data will only be retrievable from this function if it has been previously sent to the output class by one of the CodeIgniter functions like $this->load->view().

Parameters:$output (string) – Additional output data to append
Returns:CI_Output instance (method chaining)
Return type:CI_Output

Appends data onto the output string.

set_header($header[, $replace = TRUE])
  • $header (string) – HTTP response header
  • $replace (bool) – Whether to replace the old header value, if it is already set

CI_Output instance (method chaining)

Return type:


Permits you to manually set server headers, which the output class will send for you when outputting the final rendered display. Example:

$this->output->set_header('HTTP/1.0 200 OK');
$this->output->set_header('HTTP/1.1 200 OK');
$this->output->set_header('Last-Modified: '.gmdate('D, d M Y H:i:s', $last_update).' GMT');
$this->output->set_header('Cache-Control: no-store, no-cache, must-revalidate');
$this->output->set_header('Cache-Control: post-check=0, pre-check=0');
$this->output->set_header('Pragma: no-cache');
set_status_header([$code = 200[, $text = '']])
  • $code (int) – HTTP status code
  • $text (string) – Optional message

CI_Output instance (method chaining)

Return type:


Permits you to manually set a server status header. Example:

// Sets the header as:  Unauthorized

See here for a full list of headers.


This method is an alias for Common function set_status_header().

enable_profiler([$val = TRUE])
Parameters:$val (bool) – Whether to enable or disable the Profiler
Returns:CI_Output instance (method chaining)
Return type:CI_Output

Permits you to enable/disable the Profiler, which will display benchmark and other data at the bottom of your pages for debugging and optimization purposes.

To enable the profiler place the following line anywhere within your Controller methods:


When enabled a report will be generated and inserted at the bottom of your pages.

To disable the profiler you would use:

Parameters:$sections (array) – Profiler sections
Returns:CI_Output instance (method chaining)
Return type:CI_Output

Permits you to enable/disable specific sections of the Profiler when it is enabled. Please refer to the Profiler documentation for further information.

Parameters:$time (int) – Cache expiration time in seconds
Returns:CI_Output instance (method chaining)
Return type:CI_Output

Caches the current page for the specified amount of seconds.

For more information, please see the caching documentation.

_display([$output = ''])
Parameters:$output (string) – Output data override
Return type:void

Sends finalized output data to the browser along with any server headers. It also stops benchmark timers.


This method is called automatically at the end of script execution, you won’t need to call it manually unless you are aborting script execution using exit() or die() in your code.


$response = array('status' => 'OK');

        ->set_content_type('application/json', 'utf-8')
        ->set_output(json_encode($response, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES))


Calling this method manually without aborting script execution will result in duplicated output.