PHP sort array()

问题

I have an array which looks like:

array(
    'parent1' => array(
        name = 'somename',
        childs = array('child1', 'child2', 'child3', 'child4')
    ),
    'parent2' => array(
        name = 'somename',
        childs = array('child1')
    ),
    'parent3' => array(
        name = 'somename',
        childs = array('child1', 'child2', 'child3', 'child4', 'child5')
    )
    'parent4' => array(
        name = 'somename',
        childs = array('child1', 'child2', 'child3')
    ),
    'parent5' => array(
        name = 'somename',
        childs = array('child1', 'child2', 'child3', 'child4', 'child5', 'child6', 'child7')
    )
)

Ho do I sort parents by its childs count (asc order)? Parents and childs names should not be changed.

回答1:

Try this:

function count_sort($a, $b) {
  if (count($a) == count($b)) {
    return 0;
  }
  return (count($a) < count($b)) ? -1 : 1;
}

$test_array = array(
  'parent1' => array('child1', 'child2', 'child3', 'child4'),
  'parent2' => array('child1'),
  'parent3' => array('child1', 'child2', 'child3', 'child4', 'child5'),
  'parent4' => array('child1', 'child2', 'child3'),
  'parent5' => array('child1', 'child2', 'child3', 'child4', 'child5', 'child6', 'child7')
);

print_r($test_array);
usort($test_array, "count_sort");
print_r($test_array);

回答2:

function cmp($a, $b)
{
    if (count($a) == count($b)) {
        return 0;
    }
    return (count($a) < count($b)) ? -1 : 1;
}


uksort($array, "cmp");

回答3:

Use uasort - it sorts the array and maintains key asscociations (so you won't lose your keys)

uasort($myArray, 'countSort');

function countSort($a, $b) {
    if (count($a['childs']) == count($b['childs'])) {
        return 0;
    }

    return (count($a['childs']) < count($b['childs'])) ? -1 : 1;
}

回答4:

use uksort:

function cmp($a, $b)
{
    return count($a) - count($b);
}

uksort($yourArray, "cmp");

---

To answer the updated question, you would use uasort() as @fin1te mentioned.

function cmp($a, $b)
{
    return count($a['childs']) - count($b['childs']);
}

uasort($yourArray, "cmp");

来源：https://stackoverflow.com/questions/9380106/php-sort-array