仅按数字排序数组

Question

This is the array

$array = array(
   'list[P] = 1',
   'list[A] = 1',
   'list[F] = 2',
   'list[B] = 1'
);

This is the output I want

[0] => list[P] = 1
[1] => list[A] = 1
[2] => list[B] = 1
[3] => list[F] = 2

notice list[P] remains at the top because it is the first with value 1. So only numeric sorting

Answer 1

Try taking a look at this documentation .

As you are trying to sort a specific part of the value, then you need to write your own comparator, and therefore the only method available is the usort function.

The uksort function takes two attributes, the array and the method name that you wish to use to do your comparison. You then write this method, which takes two values as a parameters, and return a true of false, depending on whether it is greater than or less than.

Therefore, you would have to substring the values coming in, to only compare the numbers.

The following code sample seems to work

function cmp($a, $b)
{
    $a = substr($a, -1);
    $b = substr($b, -1);
    return $a >= $b;
}

$array = array(
   'list[P] = 1',
   'list[A] = 1',
   'list[F] = 2',
   'list[B] = 1'
);

usort($array, "cmp");

var_dump($array);

The same code, only using PHP's anonymous function:

$array = array(
   'list[P] = 1',
   'list[A] = 1',
   'list[F] = 2',
   'list[B] = 1'
);

usort(
   $array,
   function ($a, $b){
      $a = substr($a, -1);
      $b = substr($b, -1);
      return $a >= $b;
   }
);

var_dump($array);

Answer 2

If it is important to preserve records or keys with equal values in the same order they were input into the sort in the software you are writing then you would need a sort algorithm or method which is categorised as 'stable'. This limits the types of sort methods available to a programmer in any one country or a region within it in order to conform to the relevant rules.