preg_match_all只返回第一场比赛

Question

好的，基本上，我试图遍历大量包含文件超链接的html代码。我在用preg_match_all找到所有发生的事情。然而，它永远不会返回预期的匹配量。

快照HTML代码（值为$content）：

<a class="file_download file_ext_docx" href="/download.php?f=/LiO2beoordeling%20door%20mentor%20Maartje%20ingevuld.docx">Download file 1.docx</a><br /><em>Some text<a class="file_download file_ext_docx" href="/download.php?f=/BP3/Referenties.docx">Download file 2.docx</a> </strong><br /><strong>- Some text: <a class="file_download file_ext_docx" href="/download.php?f=/Zelfevaluatie%204.2.docx">Download file 3.docx</a> Soem text: <a class="file_download file_ext_docx" href="/download.php?f=/BP3/sz-lio.docx">Download file 4</a> </strong><br /><a class="file_download file_ext_docx" href="/download.php?f=/BP3/poplio.docx">

PHP代码：

preg_match_all('/download\.php\?f=(.*?)">/', $content, $matches);
foreach($matches as $val){
    echo $val[0] ."<br />";
}

上面的代码只为我返回第一个匹配项。奇怪的是，回荡着：

echo $val[1] ."<br />"; //Returns 2nd match
echo $val[2] ."<br />"; //Returns 3rd match
//etc

所以我想我应该数一数数组，然后把它绕成一个for循环来解决这个问题。然而：

count($matches); //Returns 1

Answer 1

你的模式是对的，但你找错了地方
当我转储你的结果时，我发现它没问题：

array(2) {
  [0]=>
  array(5) {
    [0]=>
    string(75) "download.php?f=/LiO2beoordeling%20door%20mentor%20Maartje%20ingevuld.docx">"
    [1]=>
    string(38) "download.php?f=/BP3/Referenties.docx">"
    [2]=>
    string(42) "download.php?f=/Zelfevaluatie%204.2.docx">"
    [3]=>
    string(33) "download.php?f=/BP3/sz-lio.docx">"
    [4]=>
    string(33) "download.php?f=/BP3/poplio.docx">"
  }
  [1]=>
  array(5) {
    [0]=>
    string(58) "/LiO2beoordeling%20door%20mentor%20Maartje%20ingevuld.docx"
    [1]=>
    string(21) "/BP3/Referenties.docx"
    [2]=>
    string(25) "/Zelfevaluatie%204.2.docx"
    [3]=>
    string(16) "/BP3/sz-lio.docx"
    [4]=>
    string(16) "/BP3/poplio.docx"
  }
}

Answer 2

首先，你应该仔细阅读php。net文档http://php.net/manual/en/function.preg-match-all.php

但是在resume中，preg_match_all根据您使用的标志放入$matches结果：preg_PATTERN_默认顺序，因此$matches数组应该是

命令的结果是，$匹配[0]是一个完整模式匹配的数组，$匹配[1]是一个由第一个括号内的子模式匹配的字符串数组，依此类推。

就你而言：

Array
(
    [0] => Array
        (
            [0] => download.php?f=/LiO2beoordeling%20door%20mentor%20Maartje%20ingevuld.docx">
            [1] => download.php?f=/BP3/Referenties.docx">
            [2] => download.php?f=/Zelfevaluatie%204.2.docx">
            [3] => download.php?f=/BP3/sz-lio.docx">
            [4] => download.php?f=/BP3/poplio.docx">
        )

    [1] => Array
        (
            [0] => /LiO2beoordeling%20door%20mentor%20Maartje%20ingevuld.docx
            [1] => /BP3/Referenties.docx
            [2] => /Zelfevaluatie%204.2.docx
            [3] => /BP3/sz-lio.docx
            [4] => /BP3/poplio.docx
        )

)

所以如果你想列出所有的结果，你可以

foreach($matches[0] as $val){
    echo $val ."<br />";
}