====== buttonDataCode() and buttonDataGet() ======

The two functions ''buttonDataCode()'' and ''buttonDataGet()'' allow buttons to be placed on a questionnaire page which repeat the current page and can trigger functions there.

The ''buttonDataCode()'' function creates a button, stores data and returns the HTML code for the button.

''string **buttonDataCode**(string //content//, [mixed //data//], [array|string //CSS-class//])''

  * //content// -- HTML code to be displayed as the content of the button.
  * //data// -- Data to be stored for the button, e.g. a number, text or an array.
  * //CSS-class// -- One or more CSS classes to be used for the button.

The ''buttonDataGet()'' function checks whether a button created with ''buttonDataCode()'' has previously been pressed and returns the data stored for it. If no data was hit or if no button was pressed, the function returns ''NULL''.

''mixed **buttonDataGet()**''


===== Example =====

In this example, the button simply passes the string "again". If the page is therefore repeated, the PHP code counts up a [[en:create:questions:internal|internal variable]] IV01_01 and shows a different question on the page depending on the variable.

<code php>
// Check current counter,
// the (int) ensures that a 0 is sent on the first call,
// the 'code:ifany' suppresses a warning on the first call
$number = (int)value('IV01_01', 'code:ifany');

// increment the number if necessary and update the internal variable
$data = buttonDataGet();
if ($data == 'again') {
 $number = $number + 1;
 put('IV01_01', $number);
}

// Display question - depending on the number
// (the entries in the array have the indices 0 to 4)
$questions = [
 'AB01',
 'AB02',
 'AB03',
 'AB04',
 'AB05'
];
question($questions[$number]);

// Include button on the page - but only if there are still questions left
if ($number < count($questions) - 1) {
 $htmlButton = buttonDataCode('Next question', 'again');
 html('<div style="margin: 1em 0; text-align: center;">'.$htmlButton.'</div>');
}
</code>