Get Number Of Days Between Two Days

$FromDate = date("Y-m-d");
$ToDate = date("Y-m-d", mktime(0,0,0,date("m"),date("d")+6,date("Y")));

$nuber_of_days = date('d',mktime(0,0,0,date("m"),date("d")+6,date("Y")) - mktime(0,0,0,date("m"),date("d"),date("Y")));

if(substr($nuber_of_days,0,1) == 0)
$nuber_of_days = substr($nuber_of_days,1,1);