Development/Tutorials/Programming Tutorial KDE 4/How to write an XML parser

A parser is used to distinguish between formal language and bulk data of a given grammar. See en.wikipedia.org/wiki/Parser if in doubt. There are two ways to write a parser: to split up the content of a file into an object as known from object-oriented programming or to trigger a function everytime a reader occurs a given syntax tag. In the following code, a function is triggered for every time an html tag is found in a file. The first file is hello.cpp: <highlightSyntax language="cpp"> /* hello.cpp compile it with g++ -I. -I/home/kde-devel/kde/include -I/home/kde-devel/qt-unstable/include/Qt -I/home/kde-devel/qt-unstable/include -I/home/kde-devel/qt-unstable/include/QtXml parser.h parser.cpp hello.cpp -L/home/kde-devel/kde/lib -L/home/kde-devel/qt-unstable/lib -lQtCore_debug -lQtXml_debug -lkdeui

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1. include <qstring.h>
2. include <QXmlInputSource>
3. include <qfile.h>
4. include <parser.h>

int main() {

 Parser* handler=new Parser();
 QXmlInputSource* source=new QXmlInputSource(new QFile("hello.htm"));
 QXmlSimpleReader reader;
 reader.setContentHandler( handler );
 reader.parse( source );

} </highlightSyntax>