在使用 PHP/SimpleXML 添加条目时，有没有办法向 XML 文件添加自动增量 - is there a way to add an auto increment to an xml file when adding entries using php/simplexml?

is there a way to add an auto increment to an xml file when adding entries using php/simplexml?

这是我添加条目的表格。我想做的是当我将表单提交到 php 文件进行处理并将条目添加到 xml 文件中时，我希望它自动增加我在 xml 文件中获得的 ID 标签。

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>Add an Entry to the Book Database</title>
<style>
table{
    width:600px;
    border:5px dotted black;
    border-radius:10px;
    padding:10px;
    margin:10px;
    }
</style>
</head>

<body>
<form action="addbook.php" method="post">
<table>
<tr>
    <td>Title:</td> 
    <td><input type="text" name="title" /></td>
</tr>
<tr>
    <td>Author:</td> 
    <td><input type="text" name="author" />(<strong>Last Name, First Name</strong>)</td>
</tr>
<tr>
    <td>Publisher:</td> 
    <td><input type="text" name="pub" /></td>
</tr>
<tr>
    <td>Edition:</td> 
    <td><input type="text" name="edition" /></td>
</tr>
<tr>
    <td>Cover:</td> 
    <td><input type="text" name="cover" />(<em>put file in directory "covers", this entry should be formatted "covers/*****.jpg" <strong>with the quotation marks</strong></em>)</td>
</tr>
<tr>
    <td>Genre:</td> 
    <td><input type="text" name="genre" />(<em>if non-fiction, format as "Non-Fiction, *****" where **** is type of non-fiction.  Self-Help, Biographical, Philosophical, etc</em>)</td>
</tr>
<tr>
    <td>Have I Read?:</td> 
    <td><input type="text" name="read" />(<em>"Yes", "No", "Partial"</em>)
</td>
</tr>
</table>
<input type="submit" value="Add Book" />

</form>
</body>
</html>

这是 php 表单处理程序

<?php
$title = $_POST["title"];
$author = $_POST["author"];
$pub = $_POST["pub"];
$edition = $_POST["edition"];
$cover = $_POST["cover"];
$genre = $_POST["genre"];
$read = $_POST["read"];

$xml = simplexml_load_file("books.xml");
$addbook = $xml->addChild("book");
$addbook->addChild("title", $title);
$addbook->addChild("author", $author);
$addbook->addChild("pub", $pub);
$addbook->addChild("edition", $edition);
$addbook->addChild("cover", $cover);
$addbook->addChild("genre", $genre);
$addbook->addChild("read", $read);
$dom = new DOMDocument("1.0");
$dom->preserveWhiteSpace = false;
$dom->formatOutput = true;
$dom->loadXML($xml->asXML());
$dom->save("books.xml"); 
header("Location:add_book_form.html");
?>

最后，这里是 XML 文件的示例

<book>
    <title>The Alphabet of Manliness</title>
    <author>Maddox</author>
    <pub>Citadel Press</pub>
    <edition>First, 2006</edition>
    <cover>"covers/alphabetmanliness.jpg"</cover>
    <genre>Humor</genre>
    <read>Yes</read>
    <id>0016</id>
</book>
<book>
    <title>Atheist Manifesto</title>
    <author>Onfray, Michel</author>
    <pub>Arcade Publishing</pub>
    <edition>First, 2007</edition>
    <cover>"covers/atheistmanifesto.jpg"</cover>
    <genre>Non-Fiction, Philosophy</genre>
    <read>Partial</read>
    <id>0017</id>
</book>

在添加标题、作者等方面一切正常。我只需要一种方法来检查最后一个 id，向其添加一个，并用它标记新条目。使用SimpleXML可以吗？

是的，有可能：

$ids = $xml->xpath("//book/id"); // select all ids
$newid = max(array_map("intval", $ids)) + 1; // change objects to `int`, get `max()`, + 1

查看它的工作原理：http://codepad.viper-7.com/qi19Ef