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我是一名初级程序员，试图制作一个简单的应用程序，只抓取网站并返回值。

我正在尝试做一些我认为很简单的事情，但是在搜索和尝试之后，我放弃了只是问。

使用我的爬虫，我返回三个变量：$title1、$title2和$title3。所有的 $title 都来自我试图找到文章名称的不同方法。理想情况下，我只需要寻找一个并完成，但有些网站以不同的方式存储数据（有些通过元标记、隐藏的 div、元素等）。

我需要一种方法来执行以下伪代码：

if $title1, $title2, $title3 != null { // don't count a string if it is null

    $title1_stringlength = string_length($title1) //find string length of the $titles
    $title2_stringlength = string_length($title2)
    $title3_stringlength = string_length($title3)

    $realtitle = $lowestvalueofstringlength; // $realtitle gets whichever $title is shortest in length, not counting any null $title's

}

这是我为什么需要这样做的一个例子：

echo $title1; //echoes "Exercise Daily"
echo $title2; //echoes "null"
echo $title3; //echoes "Exercise Daily - And More advice on SaveTheTwinkie.org"
$realtitle = $title1;//should be $title1 because it was shortest that wasn't null

//or a different example from another site

echo $title1; //echoes "Wow look at this Article Title!"
echo $title2; //echoes "null"
echo $title3; //echoes "Wow look at this Article Title! - from StupidArticles.tv"
$realtitle = $title1;//should be $title1 because it was shortest that wasn't null

因此，我的代码将查找字符串长度中最短的 $title（不为空）并将值赋予 $realtitle。

感谢您的任何帮助！如果您需要更多详细信息，请询问！

编辑

这是我的完整代码：它一直有效，直到 $title 之一是“”，然后 $realtitle 也变为“”

<?php

$sites_html = file_get_contents($url);

$html = new DOMDocument();
@$html->loadHTML($sites_html);
$title1 = null; //reset
$title2 = null; //reset
$title3 = null; //reset

//Get all meta tags and loop through them.
foreach($html->getElementsByTagName('meta') as $meta) {
    if($meta->getAttribute('property')=='og:title'){ 
        //Assign the value from content attribute to $title1
        $title1 = $meta->getAttribute('content');
    }
}
foreach($html->getElementsByTagName('h1') as $div) {
    if($div->getAttribute('itemprop')=='name'){
        $title2 = $div->nodeValue;
    }
}
foreach($html->getElementsByTagName('h1') as $div) {
    if($div->getAttribute('class')=='fn'){
        $title3 = $div->nodeValue;
    }
}

$realtitle = array_reduce(array($title2, $title1, $title3), function($a, $b) {
    return strlen($a) && $a != 'null' && strlen($a) < strlen($b) ? $a : $b;
}, null);

    echo 'metaogtitle: '.$title1 . '<br/><br/><br/><br/><br/>';
    echo 'name: '.$title2. '<br/><br/><br/><br/><br/>';
    echo 'name2: '.$title3. '<br/><br/><br/><br/><br/>';
    echo 'realtitle: '.$realtitle. '<br/><br/><br/><br/><br/>';
?>
4

3 回答 3

2 
// Filter invalid values
$titles = array_filter($titles, function($title) { return $title && $title != 'null'; }); 
// Just  sort :)
usort ($titles, function ($left, $right) { return strlen($left) - strlen($right); });
echo $titles[0];
于 2013-01-06T22:02:56.550 回答
1

这是一个适用于无限数量字符串的变体：

$shortest = NULL;

$shortestReduce = function ($string) use (&$shortest) {

    if ( ($string === "null") || !($len = strlen($string))) {
        return $shortest;
    }

    if (!isset($shortest) || $len < strlen($shortest)) {
        $shortest = $string;
    }

    return $shortest;
};

$shortestReduce($string1);
$shortestReduce($string2);
$shortestReduce($string3);
# ...

echo $shortest; # "Exercise Daily"

此 reduce 允许您对生成一个结果的多个值应用相同的函数，这里最短的字符串不是"null".

于 2013-01-06T22:23:46.473 回答
0

这个应该工作：

function real_title($titles) {
    /* Gets array of titles.
       Return the shortest that isn't null.
    */

    $min_length = strlen($titles[0]);
    $real_title = $titles[0];

    foreach ($titles as $single_title) {
       $title_length = strlen($single_title);
       if (($title_length < $min_length) && ($title_length > 0)) {
                $min_length = $title_length;
                $real_title = $single_title;
        }
    }

    return $real_title;
}
于 2013-01-06T22:03:33.253 回答