c# - 从方法返回值

Question

我有以下代码：

public class Request
{
    static string username = "ha@gmail.com";

    public string Send()
    {
        ///some variables           

        try
        {
            ///
        }

        catch (WebException e)
        {
            using (WebResponse response = e.Response)
            { 
                HttpWebResponse httpResponse = (HttpWebResponse)response;
                Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
                using (Stream Data = response.GetResponseStream())
                {
                    string text = new StreamReader(Data).ReadToEnd();                
                }
            }
        }
        return text;
    }

}  

出现错误：当前上下文中不存在“文本”。如何从方法中返回“文本”值。

Answer 1

public string Send()
{
    //define the variable outside of try catch
    string text = null; //Define at method scope
    ///some variables           
    try
    {
        ///
    }

    catch (WebException e)
    {
        using (WebResponse response = e.Response)
        {
            HttpWebResponse httpResponse = (HttpWebResponse)response;
            Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
            using (Stream Data = response.GetResponseStream())
            {
                text = new StreamReader(Data).ReadToEnd();
            }
        }
    }
    return text;
}

Answer 2

public string Send()
{
    try {
        return "Your string value";
    }

    catch (WebException e) {
        using (WebResponse response = e.Response) { 
            HttpWebResponse httpResponse = (HttpWebResponse)response;
            Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
            using (Stream Data = response.GetResponseStream())
            {
               return new StreamReader(Data).ReadToEnd();
            }
        }
    }
}

Answer 3

您必须先初始化变量才能在try clause以下范围内使用它try：

public string Send()
{
    string text = null;

    try 
    {

    }
    catch (WebException e)
    {
        using (WebResponse response = e.Response)
        {
            HttpWebResponse httpResponse = (HttpWebResponse)response;
            Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
            using (Stream Data = response.GetResponseStream())
            {
                text = new StreamReader(Data).ReadToEnd();
            }
        }
    }

    return text;
}

Answer 4

您需要定义text为 in 中的局部变量Send()，而不是像 here inside 那样的子局部块内部using(...)。这样它只会在那里有效。