PHP - 如何将数组的空值移动到其最后位置

How can I move the empty values of an array to its last position?

For example:

$givenArray = array( 
                    0=>'green', 
                    1=>'', 
                    2=>'red', 
                    3=>'', 
                    4=>'blue'
                  );

$requiredArray = array(
                       0=>'green',
                       1=>'red',
                       2=>'blue',
                       3=>'',
                       4=>'' 
                      );

Provided that the non empty values should not be sorted. It should be as it is, i.e. only the empty values should move to the end of an array.

I need exactly what my examples show.

There are much better/more elegant answers in this thread already, but this works too:

//strip empties and move to end
foreach ($givenArray as $key => $value)
{ 
    if ($value === "")
    { 
        unset($givenArray[$key]);
        $givenArray[] = $value;
    }
}

// rebuild array index
$givenArray = array_values($givenArray);

Codepad demo

There is usort($array, $callback) function that will sort with your own custom callback.

Try using usort.

function empty_sort ($a, $b) {
    if ($a == '' && $b != '') return 1;
    if ($b == '' && $a != '') return -1;
    return 0; 
}

usort($array, 'empty_sort');

Which gives (Demo):

Array
(
    [0] => blue
    [1] => green
    [2] => red
    [3] => 
    [4] => 
)

$givenArray = array(
                    0=>'green',
                    1=>'',
                    2=>'red',
                    3=>'',
                    4=>'blue'
                  );

foreach($givenArray as $value){
    if(empty($value)){
        $newarray[] = $value;
    }else{
        $filledarray[] = $value;
    }
}
$requiredArray = array_merge($filledarray,$newarray);

This should work:

function sortempty( $a, $b ) {
    return empty( $a );
}

usort( $array, 'sortempty' );

Output (Demo):

Array
(
    [0] => blue
    [1] => green
    [2] => red
    [3] => 
    [4] => 
)

usort() allows you to sort an array using a user-defined function. I return if $a is empty or not. If it's empty, return 1 which makes value $a shift right (or down) in the array.

You are looking for all values not being an empty string ("") first and then all values being an empty string:

$requiredArray = array_diff($givenArray, array('')) 
                 + array_intersect($givenArray, array(''));

This will give you:

array(5) {
  [0]=> string(5) "green"
  [2]=> string(3) "red"
  [4]=> string(4) "blue"
  [1]=> string(0) ""
  [3]=> string(0) ""
}

Which has the benefit that it preserves key => value association. If you need to renumber the keys, just apply the array_values function:

$requiredArray = array_values($requiredArray);

This will turn it into your required layout (Demo):

array(5) {
  [0]=> string(5) "green"
  [1]=> string(3) "red"
  [2]=> string(4) "blue"
  [3]=> string(0) ""
  [4]=> string(0) ""
}