# The XML C parser and toolkit of Gnome

## The tree output

Developer Menu

- Main Menu
- Reference Manual
- Code Examples
- XML Guidelines
- Tutorial
- The Reader Interface
- ChangeLog
- XSLT
- Python and bindings
- libxml2 architecture
- The tree output
- The SAX interface
- Memory Management
- I/O Interfaces
- The parser interfaces
- Entities or no entities
- Namespaces
- Upgrading 1.x code
- Thread safety
- DOM Principles
- A real example
- flat page, stylesheet

API Indexes

- Alphabetic
- Constructors
- Functions/Types
- Modules
- Symbols

Related links

- Mail archive
- XSLT libxslt
- DOM gdome2
- XML-DSig xmlsec
- FTP
- Windows binaries
- Solaris binaries
- MacOsX binaries
- lxml Python bindings
- Perl bindings
- C++ bindings
- PHP bindings
- Pascal bindings
- Ruby bindings
- Tcl bindings
- Bug Tracker

The parser returns a tree built during the document analysis. The value returned is an xmlDocPtr (i.e., a pointer to an xmlDoc structure). This structure contains information such as the file name, the document type, and a children pointer which is the root of the document (or more exactly the first child under the root which is the document). The tree is made of xmlNodes, chained in double-linked lists of siblings and with a children<->parent relationship. An xmlNode can also carry properties (a chain of xmlAttr structures). An attribute may have a value which is a list of TEXT or ENTITY_REF nodes.

Here is an example (erroneous with respect to the XML spec since there should be only one ELEMENT under the root):

In the source package there is a small program (not installed by default) called xmllint which parses XML files given as argument and prints them back as parsed. This is useful for detecting errors both in XML code and in the XML parser itself. It has an option --debug which prints the actual in-memory structure of the document; here is the result with the example given before:

    DOCUMENT
    version=1.0
    standalone=true
      ELEMENT EXAMPLE
        ATTRIBUTE prop1
          TEXT
          content=gnome is great
        ATTRIBUTE prop2
          ENTITY_REF
          TEXT
          content= linux too
        ELEMENT head
          ELEMENT title
            TEXT
            content=Welcome to Gnome
        ELEMENT chapter
          ELEMENT title
            TEXT
            content=The Linux adventure
          ELEMENT p
            TEXT
            content=bla bla bla ...
          ELEMENT image
            ATTRIBUTE href
              TEXT
              content=linus.gif
          ELEMENT p
            TEXT
            content=...

This should be useful for learning the internal representation model.

Daniel Veillard