使用PHP将XML转换为关联数组

Can anyone help with converting data from an XML document into an associative array? I'm running into issues given that the XML structure is sort of 3D and the array is more of a 2D structure (please forgive my lack of correct terminology throughout). The XML elements have attributes, children and grand-children (but I never know their names), so I figured I'd try to make the key in the array a concatenation of each child/attribute name and the value equal to, well, the value. Trouble is I need the attribute name and value as part of the concatenated array key to make it unique...Can anyone help with converting data from an XM