使用数组：使用简单条件从数组中提取数组

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.

Answer 1

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