如何在PHP中执行数据流和列表(排除列表)之间的设置差异

Question

我有一个循环中的数据流。这将从数据库中逐行检索结果。但是，我希望在流和给定数组之间设置一种数组差异形式。给定的数组是一个排除列表，例如黑名单上的用户列表。到目前为止，这就是我所拥有的。

这是一个虚构的例子。我不想写所有数据库代码逐行检索结果

database objects containing ("Volvo","BMW","Toyota");  //assume that this is a continous stream of data from a database where we don't know the total elements. Just that single element
$toys=array("BMW","Toyota");          //assume that this is a list of blacklisted users
for($rindex=0; $rindex < count($cars); $rindex++)
{

    for($index=0; $index < size(database objects); $index++)
    {
        //obtain the database object on a row by row basis
        if (strcmp ( $cars[$rindex] , $toys[$index] )!=0)  //specify exclusion
        {
        echo $cars[$rindex];

    }
    }
}

预期的答案应该是Volvo。如果我们知道$cars中的所有元素，所以不能使用array-diff($cars,$toys)，这是很容易做到的。假设$cars是一个连续流，假设数据库结果是逐行的。我们如何在固定的已知黑名单数组和连续数据流之间执行array-diff()？

记住，不能使用array-diff()，因为我们在开始时不知道数据流的全部大小或流中的所有元素。

这可以使用array-filter()完成，但我已经存在性能问题，并希望在线执行此操作。

请用PHP提供答案。

Answer 1

快速查找数组--对代码进行注释和测试。PHP 5.3.18

<?php // Q22754093

// database objects containing ("Volvo","BMW","Toyota");  //assume that this is a continous stream of data from a database where we don't know the total elements. Just that single element
$allToys = array("Volvo","BMW","Toyota");


// use the 'toy' as the array key -- there is no faster way of checking whether
// something is in an array, especially if the array is large.
$badToys = array("BMW"     => true,
                 "Toyota"  => true);          //assume that this is a list of blacklisted users
                                              // by setting them false then you treat them as
                                             // 'good' if you wish - whatever


$checkedGoodToys = array();
$checkedBadToys  = array();

//obtain the database object on a row by row basis
foreach($allToys as $oneToy)
{
   if (isBadToy($oneToy)) {
       // do what you want with the bad toy...
       $checkedBadToys[] = $oneToy;
   }
   else {
       // do what you want with the good toy...
       $checkedGoodToys[] = $oneToy;
   }
}

var_dump($checkedGoodToys, 'The Good Toys');
var_dump($checkedBadToys,  'The Bad Toys');
exit;

// check if the toy is in the badToy array
function isBadToy($theToy)
{
    global $badToys;

    return isset($badToys[$theToy]) && $badToys[$theToy];
}

Answer 2

in_array()做到了这一点。谢谢你的回答。

database objects containing ("Volvo","BMW","Toyota");  //assume that this is a continous  stream of data from a database where we don't know the total elements. Just that single element
$toys=array("BMW","Toyota");          //assume that this is a list of blacklisted users
for($rindex=0; $rindex < count($cars); $rindex++)
{

    for($index=0; $index < size(database objects); $index++)
    {
        //obtain the database object on a row by row basis
        if (in_array($cars[$rindex] , $toys)  //specify exclusion
        {
           echo $cars[$rindex];

        }
    }
}