Using Variable in foreach() as array name PHP

Question

I have been making a clock which displays schedules based on which day it is so I have created 7 arrays with schedules in them. Now I need to write a foreach statement that takes the date:

 $day = date("D");

Then uses the foreach function on that array like:

 foreach ($day as &$value) {
 }

When I do this though it gives me an error because it wants me to use the direct array variable.

Warning: Invalid argument supplied for foreach() in /home/johfin16/johnfinberg.com/php/functions-new.php on line 24

Here is an example of one of my arrays.

 $Mon = array("08:10am-08:30am-Morning Meeting",
              "08:35am-09:55am-A Block", 
              "10:05am-11:25am-B Block",
              "11:30am-12:05pm-First Lunch",
              "12:05pm-12:40pm-Second Lunch", 
              "12:40pm-02:00pm-C Block", 
              "02:05pm-03:25pm-D Block");

Is there a way to work around this without creating a bunch of if statements?

you must use switch() not foreach() because $day is a string — Mo Shal
– Mo Shal, Commented Apr 29, 2017 at 20:53
Why do you think you need to use foreach when there's just one day? — Barmar
– Barmar, Commented Apr 29, 2017 at 20:54
In each day there are multiple classes which need to be pulled from the array. — John Finberg
– John Finberg, Commented Apr 29, 2017 at 20:57
When you ask a question about an error ALWAYS include the error log. Add error_reporting(E_ALL); ini_set('display_errors', 1); at the top of your php script, what does it return? — Pedro Lobito
– Pedro Lobito, Commented Apr 29, 2017 at 21:00

Barmar · Accepted Answer · 2017-04-29 21:15:28Z

1

It looks like you're trying to use variable variables. So it should be:

$day = &${date('D');
foreach ($day as &$value) {
    ...
}

However, variable variables are generally poor programming practice. Whenever you find yourself needing them, it's a sign that you should be using an associative array instead of separate variables. So your code should be:

$calendar = array(
    'Mon' => array("08:10am-08:30am-Morning Meeting","08:35am-09:55am-A Block", "10:05am-11:25am-B Block", "11:30am-12:05pm-First Lunch", "12:05pm-12:40pm-Second Lunch", "12:40pm-02:00pm-C Block", "02:05pm-03:25pm-D Block"),
    'Tue' => array(...),
    ...
);

Then you can do:

$day = &$calendar[date('D')];
foreach ($day as &$value) {
    ...
}

edited Apr 29, 2017 at 21:15

answered Apr 29, 2017 at 21:13

Barmar

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2 Comments

Barmar Over a year ago

@Martin Thanks. Feel free to edit obvious typos like that.

Mm-Art-In Over a year ago

I would, but as it was a brand new answer I often find that the writer edits the answer, and it's a waste of time if I fix the typo while you're editing and then you save and overwrite my previous fix.... I've had this a few times so was just mentioning incase you were already on an edit :-)

John Finberg · Accepted Answer · 2017-04-29 21:10:25Z

0

The switch function can be used to set one array to $active and then that array can be used in the foreach function. Ex:

switch ($day) {
case "Mon":
    $active = $Mon;
    break;
case "Tue":
    $active = $Tue;
    break;
case "Wed":
    $active = $Wed;
    break;
default:
    $active = $Special;
}

answered Apr 29, 2017 at 21:10

John Finberg

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Comments

Mm-Art-In · Accepted Answer · 2017-04-29 21:10:56Z

0

In each day there are multiple classes which need to be pulled from the array.

NO

Because you have:

$day = date("D");

So whatever $day contained before this line is reached, classes, arrays, variables, etc. is forgotten and $day suddenly just becomes ONLY the result of date("D").

You may be wanting to add date("D") as an array element (ie one of numerous items in an array), therefore you would do:

$day[] = date("D");

This will add the date("D") value to an array of multiple $days, this can then be cycled through with a foreach loop. For each day.

answered Apr 29, 2017 at 21:10

Mm-Art-In

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