如何在asp.net2.0中实现如下代码？

Question

由于我在使用以下类时使用的是 asp.net2.0，因此出现以下错误。

Error 1 : The type or namespace name 'var' could not be found (are you missing a using directive or an assembly reference?)

我用过的类。如何在asp.net2.0中使用这段代码而不会出错

public static XElement GetGeocodingSearchResults(string address)
{
    // Use the Google Geocoding service to get information about the user-entered address
    // See http://code.google.com/apis/maps/documentation/geocoding/index.html for more info...
    var url = String.Format("http://maps.google.com/maps/api/geocode/xml?  
    address={0}&sensor=false", HttpContext.Current.Server.UrlEncode(address));

    // Load the XML into an XElement object (whee, LINQ to XML!)
    var results = XElement.Load(url);

    // Check the status
    var status =results.Element ("status").Value;
    if (status != "OK" && status != "ZERO_RESULTS")
        // Whoops, something else was wrong with the request...
        throw new ApplicationException("There was an error with Google's Geocoding Service: " + status);

    return results;
}

Answer 1

var 只是右侧表达式的实际类型的shortcut。

public static XElement GetGeocodingSearchResults(string address)
{
    // Use the Google Geocoding service to get information about the user-entered address
    // See http://code.google.com/apis/maps/documentation/geocoding/index.html for more info...
    string url = String.Format("http://maps.google.com/maps/api/geocode/xml?address={0}&sensor=false",
       HttpContext.Current.Server.UrlEncode(address));

    // Load the XML into an XElement object (whee, LINQ to XML!)
    XElement results = XElement.Load(url);

    // Check the status
    string status =results.Element ("status").Value;
    if (status != "OK" && status != "ZERO_RESULTS")
        // Whoops, something else was wrong with the request...
        throw new ApplicationException("There was an error with Google's Geocoding Service: " + status);

    return results;
}

但是 LINQ to XML（以及整个 LINQ 功能）仅在 .NET 3.5 及更高版本中可用。您应该升级到 .NET 3.5 或 switch to System.Xml