my libxml2-dev : 2.7.8.dfsg-5.1ubuntu4.6


tree.h 

/**
 * xmlAttr:
 *
 * An attribute on an XML node.
 */
typedef struct _xmlAttr xmlAttr;
typedef xmlAttr *xmlAttrPtr;
struct _xmlAttr {
    void           *_private;	/* application data */
    xmlElementType   type;      /* XML_ATTRIBUTE_NODE, must be second ! */
    const xmlChar   *name;      /* the name of the property */
    struct _xmlNode *children;	/* the value of the property */
    struct _xmlNode *last;	/* NULL */
    struct _xmlNode *parent;	/* child->parent link */
    struct _xmlAttr *next;	/* next sibling link  */
    struct _xmlAttr *prev;	/* previous sibling link  */
    struct _xmlDoc  *doc;	/* the containing document */
    xmlNs           *ns;        /* pointer to the associated namespace */
    xmlAttributeType atype;     /* the attribute type if validating */
    void            *psvi;	/* for type/PSVI informations */
};

struct _xmlNode *children;	/* the value of the property */

I can't get the value of xmlAttr.