显示与循环阵列的下一个和前一个键

Question

我相信你会喜欢它;）。

我需要一个建立浏览网页页面的导航功能（其中一些页面可以分开收集，它应该来回循环）;它应该将链接（如数字）输出到给定页面的“下一页”和“上一页”页面。

将接收数组和输入键的函数应该吐出数组给定键的值以及“next”和“previous”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“previous”。同样，如果它接收到最后一个键，它应该输出第一个键作为“下一个”。

这是我到目前为止有：

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

这应该实际工作（但没有“周期awarness”） - 你可以在http://writecodeonline.com/php/快速检查 - 如果说明迷惑你，这个代码的输出是相当自我解释... 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，所以它可能比我选择的更简单一些。

Answer 1

我觉得这是你的问题的解决方案。告诉我，如果它做你想要的（一些检查，如果你走出去的数组边界将是不错:)但我们坚持简单...）：

/* 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);