按自然降序对目录文件名数组进行排序

Question

I have a content directory to be returned in descending natural order.

I'm using scandir() and natsort() , but the addition of array_reverse() yields no results.

I've been researching using a combination of opendir() and readdir() as well what ever else to affect this outcome.

The items to be sorted are numbered image files. They are to be returned as: 10 9 8 7 and so on, but like from like 1000 999 998 997 ... until 0

Here's my current code:

$dir = 'dead_dir/dead_content/';
$launcher = scandir($dir);
natsort($launcher);
array_reverse($launcher, false);
foreach ($launcher as $value) {
    if (in_array(pathinfo($value, PATHINFO_EXTENSION), array('png'))) {
        echo '<img src="dead_dir/dead_content/'.$value.'" />'
    }
}

Answer 1

The problem is simple. array_reverse() does not modify by reference. You are confusing the behavior of sort() ing functions. Instead, you merely need to use the returned value that it generates. That said, there is a better way. Read on...

Since PHP5.4, rsort($array, SORT_NATURAL) will sort your array in DESC order and treat consecutive numbers as numbers instead of strings. This is a more direct and concise way technique versus natsort() ing then array_reverse() ing.

( Demo )
( Demo with .jpg extensions )
( Demo with static string before numbers )

I recommend using glob() to scan your directory. This way you can add the .png filter in the same call.

$dir = 'dead_dir/dead_content/';
$filepaths = glob($dir . '*.png');
rsort($filepaths, SORT_NATURAL);
foreach ($filepaths as $filepath) {
    echo '<img src="' . $filepath . '" />';
}

If you would rather omit the path and just return the filenames, just change your c urrent w orking d irectory.

chdir('dead_dir/dead_content');
$filenames = glob('*.png');
rsort($filenames, SORT_NATURAL);
foreach ($filenames as $filename) {
    echo "<div>.png filename => $filename</div>";
}

Now, if you require more specialized handling of the filenames, then a custom sorting function may serve you well.

As demonstrated in the following snippet, the spaceship operator will auto-magically type juggle digital strings as integers and give the same result as the rsort() solution above. Using the spaceship operator is still more direct than using natsort() then array_reverse() .

Code: ( Demo )

$filenames = ["10", "1", "100", "1000", "20", "200", "2"];
usort($filenames, function($a, $b) {
    return $b <=> $a;
});

var_export($filenames);

Output:

array (
  0 => '1000',
  1 => '200',
  2 => '100',
  3 => '20',
  4 => '10',
  5 => '2',
  6 => '1',
)

---

If your filenames have leading or trailing non-numeric characters, you can perform the necessary manipulations to strip the unwanted characters while comparing inside of usort() .

If anyone is not familiar with how custom sorting works with the spaceship operator...

• To achieve ASC order, write $a <=> $b .
• To achieve DESC order, write $b <=> $a .

Answer 2

 $dir='dead_dir/dead_content/';
 $launcher= scandir($dir);
 natsort($launcher);
 $r_launcher = array_reverse($launcher,true);

 foreach($r_launcher as $value ){
   if(in_array(pathinfo($value, PATHINFO_EXTENSION),array('png'))){
       echo '<img src="dead_dir/dead_content/'.$value.'" />'}}

Answer 3

If your image names will be in the format 123-image_name.jpg , 2323-image_name.jpg , ... this will do:

/**
 * Compares digits in image names in the format "123-image_name.jpg"
 *
 * @param string $img1 First image name
 * @param string $img2 Second image name
 * @return integer -1 If first image name digit is greater than second one.
 * 0 If image name digits are equal.
 * 1 If first image name digit is smaller than second one.
 */
function compareImageNames($img1, $img2){
    $ptr = '/^(\d+)-/'; // pattern

    // let's get the number out of the image names
    if (preg_match($ptr, $img1, $m1) && preg_match($ptr, $img2, $m2)) {
        $first  = (int) $m1[0]; // first match integer
        $second = (int) $m2[0]; // second match integer

        // equal don't change places
        if($first === $second) return 0;

        // if move first down if it is lower than second
        return ($first < $second) ? 1 : -1;
    } else{
        // image names didn't have a digit in them
        // move them to front
        return 1;
    }
}

// sort array
usort($images, 'compareImageNames');