数组输出结构

<?php 
    $c = count($rank); // 5

    for ($i = 0; $i < $c; $i++) {
        $labels [] = array("value" =>$i, "text" => $i);
    }

?>

output: `[{"value":1,"text":1},{"value":2,"text":2},{"value":3,"text":3},{"value":4,"text":4},{"value":5,"text":5}]`

But what I need is:

[{"value":5,"text":1},{"value":4,"text":2},{"value":3,"text":3},{"value":2,"text":4},{"value":1,"text":5}]

Any idea about that?

I'll describe my line of thinking.

What is the pattern in the sequence 5, 4, 3, 2, 1? Quite clearly, I decrease by one each time. I already know that $i increases by one each time, because that is how we wrote our for loop. My goal and what is available with $i is fairly close, so is there any way I can use $i?

Indeed there is. Instead of saying the sequence 5, 4, 3, 2, 1 decreases by one each time, I can say that the sequence increases in its distance from 5 by one each time. That is, the sequence is equivalent to 5 - 0, 5 - 1, 5 - 2, 5 - 3, 5 - 4. Notice that this lines up perfectly with $i. Therefore, our solution can be the following:

<?php 
$c = count($rank); // 5

for ($i = 0; $i < $c; $i++) {
      $labels [] = array("value" =>($c - $i), "text" => $i);
}

This takes a bit of intuition to see, and if you are in a similar situation and cannot figure out the pattern, you can always introduce a new variable.

<?php 
$c = count($rank); // 5


for ($decreasing = $c, $i = 0; $i < $c; $i++, --$decreasing) {
      $labels [] = array("value" =>$decreasing, "text" => $i);
}

Are you just wanting the value to decrement by one every time? If so subtract the iterator count from the total count:

<?php 
    $c = count($rank); // 5

    for ($i = 0; $i < $c; $i++) {
        $labels [] = array("value" =>($c - $i), "text" => $i);
    }

 ?>

How about

$labels [] = array("value" => ($c - $i), "text" => ($i + 1));

<?php 
$c = count($rank); // 5
$j = $c;
for ($i = 0; $i < $c; $i++) {
    $labels [] = array("value" =>$j, "text" => $i);
    $j --;
}
?>

The code you show won't produce that array because $i iterates over 0...4 whereas the values in your array are 1...5. But it appears that what you need to do is to change the statement inside the for loop to

$c = count($rank); // 5

for ($i = 0; $i < $c; $i++) {
  $labels[] = array("value" =>5-$i, "text" => $i+1);
}

or perhaps using array_map

$c = count($rank); // 5
$labels = array_map(function ($n) {
  return array("value" => 6-$n, "text" => $n);
}, range(1, $c));