PHP - Workaround undefined index for array

Question

I'm trying to simply add +1 to an array like this

$game['teamA']['goals']++;

But then it'll throw me an error about undefined index. And I guess that's because $game['teamA']['goals'] is not set before I am adding a value to it.

But isn't there a way to workaround this?

I could set the $game['teamA']['goals'] = 0 in start of simulation, but then I have to do that with freekicks, penalties, cards etc., AND do it for both teams. Isn't there another way of doing this?

Thanks in advance :)

so.. checking if it isset, if not add? Or is there a shorten way of using isset? — skolind
– skolind, Commented Oct 13, 2012 at 12:58
Are you asking if there's a way to test if it's already a number, before incrementing it? Or are you asking if there's some way of convincing the compiler that all unknown values should be treated as 0? — Sepster
– Sepster, Commented Oct 13, 2012 at 12:59
@Sepster that all unknown values should be treated as 0 before incrementing. — skolind
– skolind, Commented Oct 13, 2012 at 12:59
@Kolind that would be asking for trouble. Zero (in most cases - including yours, I'd say!) has meaning too. So by confusing zero with "unknown" or "undefined", would ruin the meaning of zero. — Sepster
– Sepster, Commented Oct 13, 2012 at 13:04

Luke Mills · Accepted Answer · 2012-10-13 13:01:25Z

2

You should ALWAYS initialise variables before they are used. One way to do this would be:

$game = array('teamA' => 
                  array(
                      'goals' => 0,
                      'freekicks' => 0,
                      'penalties' => 0,
                      ....
                  ),
              'teamB' =>
                  array(
                      'goals' => 0,
                      'freekicks' => 0,
                      'penalties' => 0,
                      ...
                  )
              );

answered Oct 13, 2012 at 13:01

Luke Mills

1,6261 gold badge11 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

skolind Over a year ago

I will initialise them to begin win then. Seems this is proper way of doing it. Thanks :)

Havelock · Accepted Answer · 2012-10-13 13:06:27Z

2

I'd suggest you go with a "proper initialisation", as you suggested. That would some code to your program but it's always better then on each update to check. Better do

$game = array( 'teamA' => array('goals'       => 0,
                                'freekicks'   => 0,
                                'penalties'   => 0,
                                // etc ...                       
                          ),
               'teamB' => array('goals'       => 0,
                                'freekicks'   => 0,
                                'penalties'   => 0,
                                // etc ...
                          )
        );

instead of

if(isset($game['teamA']['goals']))
    $game['teamA']['goals']++;
else
    $game[teamA]['goals'] = 1;

There's nothing wrong to properly init your variables - all of them. It's even advisable to do so.

edited Oct 13, 2012 at 13:06

answered Oct 13, 2012 at 13:01

Havelock

7,0044 gold badges37 silver badges42 bronze badges

1 Comment

skolind Over a year ago

Thanks. But i'll initialise them in the beginning. I know. I agree on you :)

Community · Accepted Answer · 2017-05-23 11:48:09Z

1

write a wrapper function to set the values.

<?php

function increment(&$dict, $key1, $key2) {
  if (!isset($dict, $key1))
    $dict[$key1] = array();
  if (!isset($dict[$key1], $key2))
    $dict[$key1][$key2] = 1;
  else
    $dict[$key1][$key2] ++;
}

$game= array();
increment($game, "teamA", "goals");
var_dump( $game);
?>

It really depends on what you expect on the runtime; if these operations are called often, it would be better to create all array indices before doing anything else, like https://stackoverflow.com/a/12873359/1689451 suggested.

edited May 23, 2017 at 11:48

CommunityBot

11 silver badge

answered Oct 13, 2012 at 13:08

Rudolf Mühlbauer

2,53118 silver badges18 bronze badges

Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

You can do one thing. Before incrementing, check for existence of the array, if not, create one! As simple as that. You can use a built-in function called isset(), which checks the existence of the variable.

Short Way:

(isset($game['teamA']['goals']) ? $game['teamA']['goals']++ : $game['teamA']['goals'] = 1;

Or using `if` condition:

if (isset($game['teamA']['goals'])
    $game['teamA']['goals']++;
else
    $game['teamA']['goals'] = 1;

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered Oct 13, 2012 at 12:59

Praveen Kumar Purushothaman

167k27 gold badges215 silver badges261 bronze badges

4 Comments

skolind Over a year ago

I know isset() exists. But did not know the shorten version of an if-sentence. I'll use that. I was looking for something as short as possible.

Havelock Over a year ago

Once again - better initialise them in the beginning.

Praveen Kumar Purushothaman Over a year ago

This is the best shorter way possible. Try it out, else I will try to get more shorter way.

skolind Over a year ago

Thanks @Praveen but I will initialise my $game array in the beginning of my script.

Collectives™ on Stack Overflow

PHP - Workaround undefined index for array

4 Answers 4

1 Comment

1 Comment

Comments

Short Way:

Or using `if` condition:

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

1 Comment

Comments

Short Way:

Or using if condition:

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related

Or using `if` condition: