PHP DatePeriod error when using DateInterval to loop over months -

i using dateinterval object loop on months. when running following code below:

 $interval = new dateinterval('p1m');  $daterange = new dateperiod('2017-08-01', $interval , '2017-10-01');   foreach($daterange $d){   $start_date = $d->format("y-m-d");   echo $start_date; }  //expected output: // 2017-08-01 // 2017-09-01 

gives following error:

fatal error: uncaught exception 'exception' message 'dateperiod::__construct(): constructor accepts either (datetimeinterface, dateinterval, int) or (datetimeinterface, dateinterval, datetime) or (string) arguments.' in c:.. stack trace: #0 c:\..: dateperiod->__construct('2017-08-01', object(dateinterval), '2017-10-01') #1 {main} thrown in c:\.. 

how can expected output?

the dateperiod constructor not used correctly. see official reference dateperiod.

try this:

$daterange = new dateperiod(     new datetime('2017-08-01'),      $interval ,      new datetime('2017-10-01') );