function arrayToXml($arr){ 
$xml = "<root>"; 
foreach ($arr as $key=>$val){ 
if(is_array($val)){ 
$xml.="<".$key.">".arrayToXml($val)."</".$key.">"; 
}else{ 
$xml.="<".$key.">".$val."</".$key.">"; 
} 
} 
$xml.="</root>"; 
return $xml; 
}

function arrayToXml($arr,$dom=0,$item=0){ 
if (!$dom){ 
$dom = new DOMDocument("1.0"); 
} 
if(!$item){ 
$item = $dom->createElement("root"); 
$dom->appendChild($item); 
} 
foreach ($arr as $key=>$val){ 
$itemx = $dom->createElement(is_string($key)?$key:"item"); 
$item->appendChild($itemx); 
if (!is_array($val)){ 
$text = $dom->createTextNode($val); 
$itemx->appendChild($text); 

}else { 
arrayToXml($val,$dom,$itemx); 
} 
} 
return $dom->saveXML(); 
} 

 <root> 

<user>

月光光abcd</user> 

<pvs>13002</pvs>

 <ips> 

<baidu_ip>1200</baidu_ip>

 <google_ip>1829</google_ip>

 </ips> 

<date>2016-06-01</date>

 </root> 

 function xmlToArray($xml){ 

 //禁止引用外部xml实体 

libxml_disable_entity_loader(true); 

$xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA); 

$val = json_decode(json_encode($xmlstring),true); 

return $val; 

}