QXmlQuery を使ってみる :Qt

.pro ファイルに追記
QT += xmlpatterns

aタグのname属性を取得する場合

	<?xml version="1.0" encoding="ISO-8859-1" ?>
	<a name="tagName"></a>

view raw data.xml hosted with ❤ by GitHub

	#include "mainwindow.h"
	#include "ui_mainwindow.h"
	#include <QFile>
	#include <QXmlQuery>
	#include <QXmlResultItems>
	MainWindow::MainWindow(QWidget *parent) :
	QMainWindow(parent),
	ui(new Ui::MainWindow)
	{
	ui->setupUi(this);
	// Open a file
	QString filename( "D:\\soft\\pleiades\\xampp\\htdocs\\www\\data.xml" );
	QFile file(filename);
	file.open(QIODevice::ReadOnly);
	// Query
	QXmlQuery query;
	query.bindVariable("fileName", &file);
	query.setQuery("declare variable $fileName external; doc($fileName)/a/@name");
	// or
	// query.setQuery("declare variable $fileName external; doc($fileName)/a/@name/data(.)");
	// Result
	QXmlResultItems xmlResultItems;
	query.evaluateTo(&xmlResultItems);
	// Try to get the first item
	QXmlItem item(xmlResultItems.next());
	while(!item.isNull())
	{
	if(item.isAtomicValue())
	{
	// Output for the query "/a/@name/data(.)"
	qDebug() << "Atomic value : " << item.toAtomicValue().toString();
	}
	else if(item.isNode())
	{
	// Output for the query "/a/@name"
	qDebug() << "Node : " << item.toNodeModelIndex().stringValue();
	}
	else
	{
	// Item must be null
	}
	// Next item
	item = xmlResultItems.next();
	}
	// Close the file
	file.close();
	}
	MainWindow::~MainWindow()
	{
	delete ui;
	}

view raw mainwindow.cpp hosted with ❤ by GitHub

結果： Node : "tagName"

---

	<?xml version="1.0" encoding="ISO-8859-1"?>
	<bookstore>
	<book category="COOKING">
	<title lang="en">Everyday Italian</title>
	<author>Giada De Laurentiis</author>
	<year>2005</year>
	<price>30.00</price>
	</book>
	<book category="CHILDREN">
	<title lang="en">Harry Potter</title>
	<author>J K. Rowling</author>
	<year>2005</year>
	<price>29.99</price>
	</book>
	<book category="WEB">
	<title lang="en">XQuery Kick Start</title>
	<author>James McGovern</author>
	<author>Per Bothner</author>
	<author>Kurt Cagle</author>
	<author>James Linn</author>
	<author>Vaidyanathan Nagarajan</author>
	<year>2003</year>
	<price>49.99</price>
	</book>
	<book category="WEB">
	<title lang="en">Learning XML</title>
	<author>Erik T. Ray</author>
	<year>2003</year>
	<price>39.95</price>
	</book>
	</bookstore>

view raw data2.xml hosted with ❤ by GitHub

	#include "mainwindow.h"
	#include "ui_mainwindow.h"
	#include <QFile>
	#include <QXmlQuery>
	#include <QXmlResultItems>
	MainWindow::MainWindow(QWidget *parent) :
	QMainWindow(parent),
	ui(new Ui::MainWindow)
	{
	ui->setupUi(this);
	// Open a file
	QString filename( "D:\\soft\\pleiades\\xampp\\htdocs\\www\\data.xml" );
	QFile file(filename);
	file.open(QIODevice::ReadOnly);
	// Query
	QXmlQuery query;
	query.bindVariable("fileName", &file);
	query.setQuery("doc($fileName)/bookstore/book[price>30]/title");
	QString testOutput;
	query.evaluateTo(&testOutput);
	qDebug() << testOutput;
	// Close the file
	file.close();
	}
	MainWindow::~MainWindow()
	{
	delete ui;
	}

view raw mainwindow2.cpp hosted with ❤ by GitHub

結果：
"<title lang="en">XQuery Kick Start</title>
<title lang="en">Learning XML</title>
"