循环显示数组的下一个和上一个键

Question

我相信你会喜欢的；）。

我需要一个功能来构建导航以浏览书中的页面（其中一些页面可能已经分开，它应该来回循环）；它应该将链接（作为数字）输出到给定页面的“下一个”和“上一个”页面。

将接收数组和输入键的函数应该吐出数组的给定键的值以及“下一个”和“上一个”值的值。 但是，如果给定的键是数组中的第一个键，它应该将数组的最后一个键输出为“前一个”。同样，如果它接收到最后一个键，它应该将第一个键输出为“next”。

这是我目前所拥有的：

$pages = array(5, 1, 6, 8);
sort($pages);

$selected = 1; // that's second key (value:5, next:6, previous:1)
// $selected = 3; // that's forth and a last key (value:8, should return next:1, previous:6)

$selected = key($pages)+$selected;

while ($pointer = current($pages)) {

if ($selected == key($pages) ) {
        echo $pointer." - current <br>";
    }
elseif($selected+1 == key($pages) ){
    echo $pointer." - next <br>";
}
elseif($selected-1 == key($pages) ){
    echo $pointer." - previous <br>";
}

else
    echo $pointer."<br>";

    next($pages);
}

这应该确实有效（但没有“循环警告”）-您可以在 http://writecodeonline.com/php/ 中快速检查-如果描述使您感到困惑，此代码的输出是不言自明的... 我相信这很容易，但我没有想法，现在是凌晨 3 点。当然，我需要最简单的解决方案，所以可能有比我选择的更简单的方法。

Answer 1

我认为这是您问题的解决方案。告诉我它是否在做你想做的事（一些检查你是否超出数组边界会很好:)但让我们坚持简单......）：

/* This is from your code */
$pages = array(5, 1, 6, 8);
sort($pages);

$selected = 1; // that's second key (value:5, next:6, previous:1)
$selected = 3; // that's forth and a last key (value:8, should return next:1, previous:6)
/* ... */

$pages_count = count($pages);
$pages_ordered = array();
$pages_ordered["current"] = $pages[$selected];


foreach($pages as $order_number => $page)
{
    if($selected == 0) {
        $pages_ordered["previous"] = $pages[$pages_count - 1];
        $pages_ordered["next"] = $pages[$selected + 1];
    } elseif($selected == ($pages_count - 1)) {
        $pages_ordered["next"] = $pages[0];
        $pages_ordered["previous"] = $pages[$selected - 1];
    } else {
        $pages_ordered["next"] = $pages[$selected + 1];
        $pages_ordered["previous"] = $pages[$selected - 1]; 
    }
}

print_r($pages_ordered);

Answer 2

说实话真的很简单。

$pages = array(5, 1, 6, 8);
sort($pages);

//how many pages do we have 
$total = count($pages);

//replace with $_GET['page']; when ready
$requested_page = rand(0, ($total -1)); //$_GET['page'];

//the selected page 
$selected = $pages[$requested_page];

//if this isn't the first page
if($selected != $pages[0]):

    //get the previous page
    $prev = $requested_page-1;

    //standard issue
    echo '<a style="margin:0 15px;" href="myscript.php?page=', $pages[$prev] ,'"> Previous </a>';
endif;


//iterate each page
foreach($pages as $page):

    //a ternary operator to assign a class if this is the current page we're on or not
    $cls = ($page == $selected ) ? 'active' : false; //for your current page class

    //you don't need the style
    echo '<a class="', $cls ,'" href="myfile.php?page=', $page ,'">', $page ,'</a>';
endforeach;

//if this is not the last page
if(selected != $pages[$total]):

    //our next page
    $next = $requested_page+1;

    //standard issue
    echo '<a href="myscript.php?page=', $pages[$next] ,'"> Next </a>';
endif;

Answer 3

试试这个功能

function get_nav($arr,$current){
    while($nav = current($arr)){
      if(key($arr)==$current){
         $prev =prev($arr);
         empty($prev)?reset($arr):''; 
         next($arr);
         $r = current($arr);
         $next = next($arr); 
         prev($arr);
         return array('prev'=>$prev,'current'=>$r,'next'=>$next);
      }
      next($arr);
    }

    return FALSE;
}

$pages = array(5, 1, 6, 8);
sort($pages);

$selected = 0;
$res = get_nav($pages,$selected);