Check if date is allowed weekday in php?

Question

I'm stuck with a problem how to check if a specific date is within allowed weekdays array in php. For example,

    function dateIsAllowedWeekday($_date,$_allowed)
    {
    if ((isDate($_date)) && (($_allowed!="null") && ($_allowed!=null))){
    $allowed_weekdays=json_decode($_allowed);
    $weekdays=array();

    foreach($allowed_weekdays as $wd){
    $weekday=date("l",date("w",strtotime($wd)));
    array_push($weekdays,$weekday);
    }
    if(in_array(date("l",strtotime($_date)),$weekdays)){return TRUE;}
    else {return FALSE;}
        }
        else {return FALSE;}
    }
 /////////////////////////////   
    $date="21.05.2010"; //actually is Friday (5)
    $wd="[0,1,2]"; //Sunday,Monday,Tuesday

    if(dateIsAllowedWeekday($date,$wd)){echo "$date is within $wd weekday values!";} 
    else{echo "$date isn't within $wd weekday values!"}

I have input dates formatted as "d.m.Y" and an array returned from database with weekday numbers (formatted as 'Numeric representation of the day of the week') like [0,1,2] - (Sunday,Monday,Tuesday).

The returned string from database can be "null", so i check it too. Then, the isDate function checks whether date is a date and it is ok.

I want to check if my date, for example 21.05.2010 is an allowed weekday in this array. My function always returns TRUE and somehow weekday is always 'Thursday' and i don't know why...

Is there any other ways to check this or what can be my error in the code above? thx

Answer 1

I'm not sure why you feel the need to convert the numeric day of the week into a string (eg "Sunday") as you only return a boolean value in the end; anyway I've removed that part and the below code should function as expected:

function dateIsAllowedWeekday($_date,$_allowed)
{
  if ((isDate($_date)) && (($_allowed!="null") && ($_allowed!=null)))
  {
    $allowed_weekdays = json_decode($_allowed);

    if (in_array(date("w", strtotime($_date)), $allowed_weekdays))
    {
      return TRUE;
    }
  }

  return FALSE;
}

Tested with 21.05.2010 (returns false), and 11.05.2010 (returns true), with your allowed_weekdays as above ([0,1,2]).

Answer 2

If you got PHP5.3 running already, you can also do:

function date_validWeekday($format, $date, array $weekdays) {
    return in_array(
        DateTime::createFromFormat($format, $date)->format('w'),
        $weekdays);
}

var_dump(date_validWeekday('d.m.Y', '21.05.2010', array(0,1,2))); // FALSE
var_dump(date_validWeekday('d.m.Y', '11.05.2010', array(0,1,2))); // TRUE

Answer 3

The reason why it keeps returning Thursday is because you are using strtotime() on single digit integer:

$weekday=date("l",date("w",strtotime($wd)));

One of the two things is happening, thought I'm not sure which:

1. the function interprets the integer as an epoch timestamp, or

2. the function is returning false, which the date function gets as a 0.

In either case, you are within 10 seconds of the original Epoch start time:

Thu, 01 Jan 1970 00:00:00 GMT

Which is on a Thursday.

Answer 4

function dateIsAllowedWeekday($_date,$_allowed){
    if ((isDate($_date)) && (($_allowed!="null") && ($_allowed!=null))){
        return in_array(date("w",strtotime($_date)),json_decode($_allowed));
    }

    return false;
}