How to wrap around in PHP array when index falls off the end?

问题

I want to be able to retrieve the value of an array by using the numeric key. The catch is that if the key is beyond the array length, I need it to loop through the array again.

$my_array = array('zero','one','two','three','four','five','six','seven');
function loopArrayValues($array,$key){
    //this is what is needed to return
    return 
}
echo "Key 2 is ".loopArrayValues($my_array,2)."<br />";
echo "Key 11 is ".loopArrayValues($my_array,11)."<br />";
echo "Key 150 is ".loopArrayValues($my_array,11)."<br />";

Expected output:

Key 2 is two
Key 11 is three
Key 150 is three

My research references:

continuously loop through PHP array (or object keys)
http://php.net/manual/en/class.infiniteiterator.php

My formed function:

function loopArrayValues($array,$key){
  $infinate = new InfiniteIterator(new ArrayIterator($array));
  foreach( new LimitIterator($infinate,1,$key) as $value){
    $return=$value;
  }
  return $return;
}

The function works, but I have a question: is this a good way to get the intended results?

回答1:

You are being far too complex, unless you actually want to process the elements in the array you don't want to iterate over them as it is expensive. I think you just need the modulus of the number of elements in the array, like this:-

$my_array = array('zero', 'one','two','three','four','five','six','seven');

function loopArrayValues(array $array, $position)
{
    return $array[$position % count($array)];
}

for($i = 0; $i <= 100; $i++){
    echo "Position $i is " . loopArrayValues($my_array, $i) . "<br/>";
}

Ouput:-

Position 0 is zero
Position 1 is one
Position 2 is two
Position 3 is three
Position 4 is four
Position 5 is five
Position 6 is six
Position 7 is seven
Position 8 is zero
Position 9 is one
Position 10 is two
Position 11 is three
Position 12 is four
Position 13 is five

etc...

来源：https://stackoverflow.com/questions/16613857/how-to-wrap-around-in-php-array-when-index-falls-off-the-end

标签

php

arrays

infinite-loop

array-key