How to create a folder after clicking on a button? I got a requirement like this: In the admin page there should be one create folder button, user can create a new folders as per his wish. How can I achieve this programaticaly. 
Till now I created a admin page there one button is also coming, but I am not getting how to proceed further.So please give some suggestions, thanks in advance.
 Below code I have tried. 

  $form['create_folder'] = array(
    '#type' =&gt; 'submit',
    '#value' =&gt; t('Create folder'),
    '#submit' =&gt; 'custom_submit',
  );
function custom_submit($form, &amp;$form_state){
  $new_folder = 'public://newfolder/';
  file_prepare_directory($new_folder, FILE_CREATE_DIRECTORY);
}


When I click on the submit button I got this warning Warning: Invalid argument supplied for foreach() in form_execute_handlers() (line 1507 of C:\xampp\htdocs\drupaltest\includes\form.inc).
The #submit property takes an array of function names rather than a single string:

$form['create_folder'] = array(
  '#type' =&gt; 'submit',
  '#value' =&gt; t('Create folder'),
  '#submit' =&gt; array('custom_submit'),
);