無法將字符串轉換爲int。錯誤信息：輸入字符串的不正確的格式

Question

我havethe以下，輸出數字「40」代碼：

Hashtable ht = new Hashtable(); 
ht.Add("numRooms", pageData.Property["romtotalt"].ToString()); 
string str = ht["numRooms"].ToString(); 
lblMigrate.Text = i.ToString(); 

然後我嘗試將字符串轉換爲一個int，我得到一個異常/錯誤：

Hashtable ht = new Hashtable(); 
ht.Add("numRooms", pageData.Property["romtotalt"].ToString()); 
string str = ht["numRooms"].ToString(); 
int i = Convert.ToInt32(str); // <-- This is where it fails I t hink. But why?? 
lblMigrate.Text = i.ToString(); 

這是錯誤消息我得到：

Server Error in '/' Application. 
Input string was not in a correct format. 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.FormatException: Input string was not in a correct format. 

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 

Stack Trace: 

[FormatException: Input string was not in a correct format.] 
    System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +7469351 
    System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +119 
    development.templates.HotellGuide.btnMigrateHotels_Click(Object sender, EventArgs e) +956 
    System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111 
    System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110 
    System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 
    System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 
    System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36 
    System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 


Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 

我不明白什麼是錯的。我以前曾經多次將int串聯到int，並且從來沒有發生過這個問題。

請幫助:)

更新

我已經找到了解決辦法。我不知道爲什麼這個工程....但它的工作原理...
我把轉換裏面的Try Catch，現在它的工作原理。圖一出：op

int numRooms = 0; 
int numAllergyRooms = 0; 

try 
{ 
    numRooms = Convert.ToInt32(newHotel["numRooms"].ToString().Trim()); 
    numAllergyRooms = Convert.ToInt32(newHotel["numAllergyRooms"].ToString().Trim()); 
} 
catch (Exception ex) 
{ 
    Console.WriteLine("{0} Exception caught.", ex); 
} 

Answer 1

我覺得「輸入字符串的格式不正確」這一行解釋了這一切。在該行

int i = Convert.ToInt32(str); 

str可能包含字母字符。在調試時看看它，它包含什麼？

Answer 2

的代碼是好的，但如果海峽可能有空白，所以你應該在轉換前刪除它們：

int i = Convert.ToInt32(str.Replace(" " ,"")); // <-- This is where it fails I t hink. But why?? 

Answer 3

您應該添加TRIM（）到您的代碼行，你認爲失敗。這可能與過多的空間有關。

int i = Convert.ToInt32(str.Trim()); 

甚至檢查，看看是否STR是的String.Empty，這也將導致Convert.ToInt32崩潰。

if (string.IsNullOrEmpty(str)) { 
    str = "0"; 
} 

Answer 4

我有同樣的問題，而只是一門心思抓方法解決我的問題

 try 
     { 
      decimal dPrice=Convert.ToDecimal(sPrice); 
      decimal dFreight = Convert.ToDecimal(sFreight); 
      decimal dLocalship = Convert.ToDecimal(sLocalship); 
      decimal dTarrif = Convert.ToDecimal(sTarrif); 
      decimal dBenefit = Convert.ToDecimal(sBenefit); 
      decimal dTax = Convert.ToDecimal(sTax); 
      decimal dVat = Convert.ToDecimal(sVat); 
      decimal dConv = Convert.ToDecimal(sConv); 
      decimal factors=(dTarrif+dBenefit+dTax+dVat)/100+1; 
      decimal dTotal=(dPrice+dFreight)*dConv; 
      dTotal=dTotal*factors; 
      string st = Convert.ToString(dTotal); 
      e.Row.Cells[iCell].Text = "price is: " + st + " Rials"; 
     } 
     catch(Exception ex) 
     { 
      Console.WriteLine("{0} Exception caught.", ex); 
     } 

Answer 5

這將是你正試圖轉換空值或在這種情況下，「」（後您的.ToString()）到INT。

嘗試插入一個可接受的佔位符，例如下面代碼中顯示的-1。

Convert.ToInt32(newHotel["numAllergyRooms"].ToString().Trim() == "" ? "-1" : newHotel["numAllergyRooms"].ToString().Trim());