<portType name="GoogleSearchPort">
<operation name="doGetCachedPage">
<input message="typens:doGetCachedPage" />
<output message="typens:doGetCachedPageResponse" />
</operation>

<operation name="doSpellingSuggestion">
<input message="typens:doSpellingSuggestion" />
<output message="typens:doSpellingSuggestionResponse" />
</operation>

<operation name="doGoogleSearch">
<input message="typens:doGoogleSearch" />
<output message="typens:doGoogleSearchResponse" />
</operation>
</portType>

</definitions>

我用以下代码提取porttype的所有operation元素，并打印operation的name，但上面都没有打印出来，是怎么回事了？？请高手指点！！！

XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(@"E:\experiment\e4\googlesimple.xml");//导入物理路径下的xml文档

XmlNodeList nodeList = xmlDoc.SelectNodes("/definitions/portType");//提取所有operation项

Console.WriteLine("tiqu");

string operationname;
foreach (XmlNode op in nodeList)//遍历portType的所有子节点
{
    XmlElement xe = (XmlElement)op;//将子节点类型转换为XmlElement类型     
    operationname = xe.GetAttribute("name");
    Console.WriteLine(operationname);
}