Working with arrays: extracting an array from an array with a simple condition

Question

I have an array:

$quizzes = array();
            $Quiz = array(
                'quiz_id'   => $quiz_id,
                'correct'   => $correctAnswers
            );
            $quizzes[] = $Quiz;

$quizzes is an array which contains many quizzes called Quiz, which in turn have $Quiz['quiz_id'] and $Quiz['correct']. Now what I'm trying to do is to select a particular quiz from the list of quizzes in $quizzes where quiz_id=1.

If such quiz exists, I would like to echo quiz is found. If no $Quiz with such id exists, echo no quiz is found.

A simple solution that I came up with is to do a foreach loop.

foreach($quizzes as $Quiz) if($Quiz['quiz_id'] == 1) {} else {}

However, since I have more than 1 quiz, it returns the else statement as many times as there are $Quiz['quiz_id'] != 1 which is many many times.

Scuzzy · Accepted Answer · 2017-04-07 00:53:56Z

3

Indexing your array such as $quizzes[ $quiz_id ] = $Quiz; would permit you to go straight to that item in the array.

So take your existing line of

$quizzes[] = $Quiz;

and change it to

$quizzes[ $quiz_id ] = $Quiz;

then you can use

if( isset( $quizzes[ $quiz_id ] ) )
{
  echo 'found the quiz!';
}
else
{
  echo 'no quiz found';
}

where $quiz_id is the id of the quiz you wish to locate

edited Apr 7, 2017 at 0:53

answered Apr 7, 2017 at 0:51

Scuzzy

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3 Comments

GRS Over a year ago

But the thing is that $quizzes[1] corresponds to some $Quiz, which does not necessarily have quiz_id of 1?

GRS Over a year ago

Or let's say $quizzes[0] is the first ever $Quiz entered. If a user completed 5th test first, I would add $Quiz into this array where quiz_id=5. Then if $quizzes[5] doesn't yet exists, but there is a quiz with quiz_id 5

GRS Over a year ago

I think I see what you mean, you are indexing the positions of these quizzes based on id, so an array can be empty for the first 100 point $quizzess[0 to 99] but have $quizzes[100] as the first one if the user completes 100th quiz

LF-DevJourney · Accepted Answer · 2017-04-07 01:48:52Z

1

$id = 1;
array_filter($quizzes, function($v) use($id) {return $v['quid_id'] == $id;});

answered Apr 7, 2017 at 1:48

LF-DevJourney

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