PHP - Convert A Date String Into Numeric Date

So this is a simple code that finds out the difference between two dates and displays it in number of days.

$date1=date_create("2013-03-15");
$date2=date_create("2013-12-12");
$diff=date_diff($date1,$date2);
echo $diff->format("%R%a days");

// RESULT
+272 days

My first question. Is it possible to remove the + sign in the result above?

Second question. Is it possible to show "months" if it's greater than 30 days? And years if the days are greater than 365?

How would I do this?

PLEASEEE no matter what  i do... datepicker always post the dates as string i do whatever ways know convert string to date but no way!! how convert string to date so i can sarch in a mysql table... tnx in advanced 

    <!--HTML-->

    <div class="control-group">
        <label class="control-label">from</label>
        <div class="controls input-append date form_date" data-date="" data-date-format='yyyy/mm/dd' data-link-format="yyyy/mm/dd">
        <input size="16" type="text" value="" id="from" name="from">
        <span class="add-on"><i class="icon-th"></i></span>
    </div>
        <input type="hidden" id="d" value="" /><br/>
    </div>
    <div class="control-group">
        <label class="control-label">tto</label>
        <div class="controls input-append date form_date" data-date="" data-date-format='yyyy/mm/dd' data-link-format="yyyy/mm/dd">
        <input size="16" type="text" value="" id="tto" name="tto">
        <span class="add-on"><i class="icon-th"></i></span>
    </div>
        <input type="hidden" id="h" value="" /><br/>
    </div>
    <div class="card-body">        
        <button type="submit" class="btn btn-secondary">search...</button>
    </div>

    <!--PHP-->

    $yfromx=$_POST['from']  ;
    $yuntilly=$_POST['untill']  ;
    $yfroma=str_replace(" ","/","$yfromx");
    $yuntillb=str_replace(" ","/","$yuntilly");

    $t1=gettype ( $yfromx ) ;
    $t2=gettype ( $yuntilly ) ;
    $yfrom=date('Y/m/d', '$yfroma');
    $yuntill=date('Y/m/d', '$yuntillb');
    $t3=gettype ( $yfrom ) ;
    $t4=gettype ( $yuntill ) ;
    echo $yfroma.' | '.$yuntillb.' | '.$t1.' | '. $t2.' | '.$t3.' | '. $t4;
    //SELECT username FROM oc_calendar WHERE start_date between '$from' AND '$to'
    $queryfebus = "SELECT distintc FROM glamm_pedidos WHERE fecha_folio between '$yfrom' AND '$yuntill';";
    //$queryfolb = "SELECT *M glamm_pedidos WHERE procesado='$yfoliox' or folio='$yfoliox' or nombre like '%$yfoliox%' or mail like '%$yfoliox%';";
    $resultfebus = mysqli_query($con,$queryfebus) or mysqli_error($con);
    blah 
    blah