错误 1 “robot.PostDate.LogIN(string, string, string)”: 并非所有的代码路径都返回值 F:\c#\robot\robot\PostDate.cs 10 30 robot
请问这个错误怎么解决。我是新手,刚接触c#还望各位多多指点!
public static string LogIN(string URI, string email, string password) 
        {
            try
            {
                CookieContainer cookieContainer = new CookieContainer();                ///////////////////////////////////////////////////
                // 1.打开 MyLogin.aspx 页面,获得 GetVeiwState & EventValidation
                ///////////////////////////////////////////////////                
                // 设置打开页面的参数
               // string URI = "http://login.xiaonei.com/Login.do";
                HttpWebRequest request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = true;                // 接收返回的页面
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                System.IO.Stream responseStream = response.GetResponseStream();
                System.IO.StreamReader reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                string srcString = reader.ReadToEnd();                // 获取页面的 VeiwState                
                string viewStateFlag = "id=\"__VIEWSTATE\" value=\"";
                int i = srcString.IndexOf(viewStateFlag) + viewStateFlag.Length;
                int j = srcString.IndexOf("\"", i);
                string viewState = srcString.Substring(i, j - i);                // 获取页面的 EventValidation                
                string eventValidationFlag = "id=\"__EVENTVALIDATION\" value=\"";
                i = srcString.IndexOf(eventValidationFlag) + eventValidationFlag.Length;
                j = srcString.IndexOf("\"", i);
                string eventValidation = srcString.Substring(i, j - i);                ///////////////////////////////////////////////////
                // 2.自动填充并提交 MyLogin.aspx 页面
                ///////////////////////////////////////////////////
                // 提交按钮的文本
                string submitButton = "登录";
                           
                // 将文本转换成 URL 编码字符串
                // viewState = System.Web.HttpUtility.UrlEncode(viewState);
                // eventValidation = System.Web.HttpUtility.UrlEncode(eventValidation);
                // submitButton = System.Web.HttpUtility.UrlEncode(submitButton);                // 要提交的字符串数据。格式形如:user=uesr1&password=123
                string formatString = "email={0}&password={1}&origURL=http%3A%2F%2Fwww.xiaonei.com%2FSysHome.do";
                string postString = string.Format(formatString, email, password, submitButton, viewState, eventValidation);                // 将提交的字符串数据转换成字节数组
                byte[] postData = Encoding.ASCII.GetBytes(postString);                // 设置提交的相关参数
                request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "POST";
                request.KeepAlive = true;
                request.ContentType = "application/x-www-form-urlencoded";
                request.CookieContainer = cookieContainer;
                request.ContentLength = postData.Length;                // 提交请求数据
                System.IO.Stream outputStream = request.GetRequestStream();
                outputStream.Write(postData, 0, postData.Length);
                outputStream.Close();                // 接收返回的页面
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("GB2312"));
                srcString = reader.ReadToEnd();                ///////////////////////////////////////////////////
                // 3.打开 Default.aspx 页面
                ///////////////////////////////////////////////////
                // 设置打开页面的参数
                
                URI = "http://apps.xiaonei.com/happyfarm";
                
                request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = true;
                request.CookieContainer = cookieContainer;                // 接收返回的页面
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                srcString = reader.ReadToEnd();
                return srcString;
                ///////////////////////////////////////////////////
                // 4.分析返回的页面
                ///////////////////////////////////////////////////
                // ...... ......            }
            catch (WebException we)
            {
                string msg = we.Message;
            }

解决方案 »

  1.   

    如果发生异常,会进去catch
    而执行了catch后,没有写这个方法的返回值。
      

  2.   

    www.xmcoa.com
      

  3.   

    你可以参考TryParse的作法:public static bool LogIN(string URI, string email, string password, out str) 
    {
        try
        {
           ....
           str=
           return true;
        }
        catch(WebException we) 
        {
          str=we.Message;
          return false
        }
    }如果返回true,说明登陆成功,而str就是你要的东西
    如果返回false,说明登陆失败,str记录着失败(异常)的原因
      

  4.   

    catch (WebException we)
    {
    string msg = we.Message;
    return msg;
    }
      

  5.   

    public static string LogIN(string URI, string email, string password) 
            { 
             string srcString=String.Empty;            try 
                { 
                    CookieContainer cookieContainer = new CookieContainer();                 /////////////////////////////////////////////////// 
                    // 1.打开 MyLogin.aspx 页面,获得 GetVeiwState & EventValidation 
                    ///////////////////////////////////////////////////                
                    // 设置打开页面的参数 
                  // string URI = "http://login.xiaonei.com/Login.do"; 
                    HttpWebRequest request = WebRequest.Create(URI) as HttpWebRequest; 
                    request.Method = "GET"; 
                    request.KeepAlive = true;                 // 接收返回的页面 
                    HttpWebResponse response = request.GetResponse() as HttpWebResponse; 
                    System.IO.Stream responseStream = response.GetResponseStream(); 
                    System.IO.StreamReader reader = new System.IO.StreamReader(responseStream, Encoding.UTF8); 
                    srcString = reader.ReadToEnd();                 // 获取页面的 VeiwState                
                    string viewStateFlag = "id=\"__VIEWSTATE\" value=\""; 
                    int i = srcString.IndexOf(viewStateFlag) + viewStateFlag.Length; 
                    int j = srcString.IndexOf("\"", i); 
                    string viewState = srcString.Substring(i, j - i);                 // 获取页面的 EventValidation                
                    string eventValidationFlag = "id=\"__EVENTVALIDATION\" value=\""; 
                    i = srcString.IndexOf(eventValidationFlag) + eventValidationFlag.Length; 
                    j = srcString.IndexOf("\"", i); 
                    string eventValidation = srcString.Substring(i, j - i);                 /////////////////////////////////////////////////// 
                    // 2.自动填充并提交 MyLogin.aspx 页面 
                    /////////////////////////////////////////////////// 
                    // 提交按钮的文本 
                    string submitButton = "登录"; 
                              
                    // 将文本转换成 URL 编码字符串 
                    // viewState = System.Web.HttpUtility.UrlEncode(viewState); 
                    // eventValidation = System.Web.HttpUtility.UrlEncode(eventValidation); 
                    // submitButton = System.Web.HttpUtility.UrlEncode(submitButton);                 // 要提交的字符串数据。格式形如:user=uesr1&password=123 
                    string formatString = "email={0}&password={1}&origURL=http%3A%2F%2Fwww.xiaonei.com%2FSysHome.do"; 
                    string postString = string.Format(formatString, email, password, submitButton, viewState, eventValidation);                 // 将提交的字符串数据转换成字节数组 
                    byte[] postData = Encoding.ASCII.GetBytes(postString);                 // 设置提交的相关参数 
                    request = WebRequest.Create(URI) as HttpWebRequest; 
                    request.Method = "POST"; 
                    request.KeepAlive = true; 
                    request.ContentType = "application/x-www-form-urlencoded"; 
                    request.CookieContainer = cookieContainer; 
                    request.ContentLength = postData.Length;                 // 提交请求数据 
                    System.IO.Stream outputStream = request.GetRequestStream(); 
                    outputStream.Write(postData, 0, postData.Length); 
                    outputStream.Close();                 // 接收返回的页面 
                    response = request.GetResponse() as HttpWebResponse; 
                    responseStream = response.GetResponseStream(); 
                    reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("GB2312")); 
                    srcString = reader.ReadToEnd();                 /////////////////////////////////////////////////// 
                    // 3.打开 Default.aspx 页面 
                    /////////////////////////////////////////////////// 
                    // 设置打开页面的参数 
                    
                    URI = "http://apps.xiaonei.com/happyfarm"; 
                    
                    request = WebRequest.Create(URI) as HttpWebRequest; 
                    request.Method = "GET"; 
                    request.KeepAlive = true; 
                    request.CookieContainer = cookieContainer;                 // 接收返回的页面 
                    response = request.GetResponse() as HttpWebResponse; 
                    responseStream = response.GetResponseStream(); 
                    reader = new System.IO.StreamReader(responseStream, Encoding.UTF8); 
                    srcString = reader.ReadToEnd(); 
                    
                    /////////////////////////////////////////////////// 
                    // 4.分析返回的页面 
                    /////////////////////////////////////////////////// 
                    // ...... ......             } 
                catch (WebException we) 
                { 
                    string msg = we.Message; 
                }
               return srcString; 
    }
      

  6.   

    return "";public static string LogIN你这里设置有返回值!
      

  7.   

                catch (WebException we) 
                { 
                    string msg = we.Message; 
                    return "";
                }
    还有就是srcString的作用域写在TRY块外面也可以,函数返回值必须是在函数域里面才可以...
      

  8.   


    //你的函数一定要有返回值的
    try
    {
        ......
        return 
    }
    catch
    {
        //或者return
        //或者抛出异常
    }
      

  9.   

    异常里没有返回值:
    catch (WebException we)
                {
                    string msg = we.Message;
                }
    改成:
    catch (WebException we)
                {
                    return we.Message;
                }