通过逗号和合并间隔将排序的数字数组内爆为字符串 [英] Implode sorted number array to string by commas and merge intervals

问题描述

我想内爆一个数组，但有一个区别.我想用 - 符号合并间隔.如何才能做到这一点?(数组是有序的！)

I would like to implode an array, but with one difference. I would like to merge intervals with a - sign. How can this be done? (The array is ordered!)

示例:

array(1,2,3,6,8,9) => "1-3,6,8-9"
array(2,4,5,6,8,10) => "2,4-6,8,10"

推荐答案

这应该适合你:

首先，对于每次迭代，我们简单地将当前迭代次数附加到 $result 字符串:

First for every iteration we simply append the current number of the iteration to the $result string:

$result .= $arr[$i];

此后，我们检查 while 循环中是否存在数组 (1) 中的下一个元素，并跟踪当前迭代中的数字 (2).我们这样做直到条件评估为假:

After this we check in a while loop if there exists a next element in the array(1) and it follows up the number from the current iteration(2). We do that until the condition evaluates as false:

//(1)Check if next element exists     (2)Check if next element follows up the prev one
      ┌───────┴───────┐    ┌───────────┴────────────┐      
while(isset($arr[$i+1]) && $arr[$i] + 1 == $arr[$i+1] && ++$range)
    $i++;

然后我们检查我们是否有一个范围(例如 1-3).如果是，那么我们将破折号和范围的结束编号附加到结果字符串中:

Then we check if we have a range (e.g. 1-3) or not. If yes then we append the dash and the end number of the range to the result string:

if($range)
    $result .= "-" . $arr[$i];

最后我们还检查我们是否在数组的末尾并且不再需要附加逗号:

At the end we also check if we are at the end of the array and don't need to append a comma anymore:

if($i+1 < $l)
    $result .= ",";

代码:

<?php

    $arr = array(1,2,3,6,8,9);
    $result = "";
    $range = 0;

    for($i = 0, $l = count($arr); $i < $l; $i++){

        $result .= $arr[$i];

        while(isset($arr[$i+1]) && $arr[$i] + 1 == $arr[$i+1] && ++$range)
            $i++;

        if($range)
            $result .= "-" . $arr[$i];

        if($i+1 < $l)
            $result .= ",";

        $range = 0;   

    }

    echo $result;

?>

输出:

1-3,6,8-9

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