How to simplify array value initialization

Question

Several times a day I run into a problem where I need to dynamically initialize variables in a multidimensional array to prevent PHP throwing a notice because of an uninitialized variable.

Code fragments like this are very common:

if(!isset($profile[$year][$month][$weekday][$hour])) {
    $profile[$year][$month][$weekday][$hour] = 0;
}
$profile[$year][$month][$weekday][$hour] += $load;

Or:

$profile[$year][$month][$weekday][$hour] 
    = isset($profile[$year][$month][$weekday][$hour]) 
    ? $profile[$year][$month][$weekday][$hour] + $load
    : $load;

That looks awful and is a pain to write, also makes maintaining quite hard as these fragments are abundant. Does anyone have any ideas how I could simplify such a task? I thought of creating a reference $r to $profile[$year][$month][$weekday][$hour] to reduce redundancy, but it will also throw a notice if not initialized properly.

Initializing the array beforehand isn't feasible as not all keys will be used and I'd like to avoid unnecessary keys.

Any tips?

Community · Accepted Answer · 2017-05-23 11:47:38Z

1

I asked the same question a few months back and got a number of good answers.

In your case, maybe set up a generic function?

Something like:

set_array_member (&$profile, $year, $month, $weekday, $hour, 0);

$result = get_array_member (&$profile, $year, $month, $weekday, $hour);

the parameter before last being the member to be set, and the last the value (or something like that, you get my drift.) You could use func_get_args() to keep the parameter count flexible.

edited May 23, 2017 at 11:47

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answered Mar 2, 2010 at 12:43

Pekka

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3 Comments

Tatu Ulmanen Over a year ago

Good idea. I need this to work on several different types on arrays, so your idea of using func_get_args() is good, but how can you check if the given key exists or not when you have the keys in an array? I can't think of any fast methods, any ideas?

Pekka Over a year ago

@Tatu I was thinking along the lines of something like if isset($args[0][$args[1]][$args[2]][$args[3]] ..... but this is indeed tricky to do with the dynamic number of arguments. Who is going to be first to say the e-word? :)

Pekka Over a year ago

@Tatu Maybe a loop using array_key_exists()? That could work. If I find the time to put some more reasoning it later, I'll update the answer. Let me know if you get anywhere with this.

Alex Weber · Accepted Answer · 2010-03-02 12:41:22Z

0

The reference idea is good, and its easier to write if(isset($r)) than what you have right now :)

That said, the only other way around this off the top of my head is (and its terrible practice and I don't recommend it) turn off notices.

answered Mar 2, 2010 at 12:41

Alex Weber

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1 Comment

Tatu Ulmanen Over a year ago

Yea, but defining the reference will cast a notice if the referenced variable doesn't exist, so I won't even get to the isset() part without a notice.

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