No <?xml version="1.0"?> declaration at beginning of output files

[fjpereny]

I've noticed that my output XML documents work fine but do not begin with <?xml version="1.0"?>

Since a well-formatted XML document requires , should an output XML document always include this header by default?

Here is an example of my code which does not include the <?xml version="1.0"?> header:

Creating Document

tinyxml2::XMLDocument* MainWindow::create_XML()
{
    tinyxml2::XMLDocument *xmlDoc = new tinyxml2::XMLDocument;
    tinyxml2::XMLNode *root = xmlDoc->NewElement("root");
    xmlDoc->InsertFirstChild(root);

    tinyxml2::XMLElement *save_date = xmlDoc->NewElement("save_date");
    root->InsertEndChild(save_date);
        QString date = QDate::currentDate().toString();
        save_date->SetText(date.toStdString().c_str());
......
......
......

Saving Document

bool MainWindow::on_actionSave_triggered()
{
    tinyxml2::XMLDocument *xmlDoc = create_XML();

    QString save_file_path = QFileDialog::getSaveFileName(this,
                                                "Save File",
                                                QDir::toNativeSeparators(QDir::currentPath()),
                                                "XML Files (*.xml)\n"
                                                "All Files (*.*)");
    if (save_file_path.isEmpty())
        return false;

    if (!save_file_path.contains(".xml"))
        save_file_path += ".xml";

    xmlDoc->SaveFile(save_file_path.toStdString().c_str());

    delete xmlDoc;
    xmlDoc = nullptr;
    return true;
}

[khReichel]

You forgot to add a delcaration item (which can be e.g. ).

So your code should looks like:

void create_XML()
{
    tinyxml2::XMLDocument *xmlDoc = new tinyxml2::XMLDocument;
    auto declaration = xmlDoc->NewDeclaration();
    tinyxml2::XMLNode *root = xmlDoc->NewElement("root");
    xmlDoc->InsertFirstChild(declaration);
    xmlDoc->InsertAfterChild(declaration, root);

    tinyxml2::XMLElement *save_date = xmlDoc->NewElement("save_date");
    root->InsertEndChild(save_date);
    save_date->SetText("2022-01-01");
    xmlDoc->SaveFile("/tmp/myxml.xml");
    delete xmlDoc;
}

the result will be:

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <save_date>2022-01-01</save_date>
</root>

@leethomason So I think this bug could be closed.