输入字符串格式不正确？

问题描述：

当我运行我的C＃代码时，出现此错误：输入字符串格式不正确。并突出显示此代码：输入字符串格式不正确？

 theTWAValue=Convert.ToInt32(theTWALabel.Text);

为什么会发生这种情况？

附加信息：

整个C＃功能：

<script runat="server"> 
       protected void YourListView_Load(object sender, EventArgs e) 
{ 
    Label theTWALabel; 
int theTWAValue; 
foreach (ListViewItem item in YourListView.Items) 
{ 
     theTWALabel = (Label)item.FindControl("TWALabel"); 
    theTWAValue = Convert.ToInt32(theTWALabel.Text); 
    if (theTWAValue >= 0) 
    { 
     if (theTWAValue < 90) 
      theTWALabel.ForeColor = System.Drawing.Color.Yellow; 
     else 
      theTWALabel.ForeColor = System.Drawing.Color.Red; 
    } 

} 
} 

       </script>

这里是代码的其余部分：

<asp:SqlDataSource id="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString %>" ProviderName="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString.ProviderName %>" SelectCommand="SELECT [Plant] FROM [PLANT]"> 
    </asp:SqlDataSource> 
    <asp:DropDownList id="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="Plant" DataValueField="Plant" Height="85px" Width="393px"> 
    </asp:DropDownList> 
    <asp:SqlDataSource id="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString %>" ProviderName="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString.ProviderName %>" SelectCommand="SELECT [Plant], [Group No#] AS column1, [Group] FROM [Temp Table that contains TWA values] WHERE ([Plant] = ?)"> 
     <SelectParameters> 
      <asp:ControlParameter ControlID="DropDownList1" Name="Plant" PropertyName="SelectedValue" Type="String" /> 
     </SelectParameters> 
    </asp:SqlDataSource> 
    <asp:DropDownList id="DropDownList2" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource2" DataTextField="Group" DataValueField="column1" Height="30px" Width="394px"> 
    </asp:DropDownList> 
    <asp:SqlDataSource id="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString %>" ProviderName="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString.ProviderName %>" SelectCommand="SELECT [Plant], [Group No#] AS column1, [Group], [Job Code] AS Job_Code, [Job Function] AS Job_Function, [Job Classification] AS Job_Classification FROM [Temp Table that contains TWA values] WHERE (([Plant] = ?) AND ([Group No#] = ?))"> 
     <SelectParameters> 
      <asp:ControlParameter ControlID="DropDownList1" Name="Plant" PropertyName="SelectedValue" Type="String" /> 
      <asp:ControlParameter ControlID="DropDownList2" Name="column1" PropertyName="SelectedValue" Type="String" /> 
     </SelectParameters> 
    </asp:SqlDataSource> 
    <asp:DropDownList id="DropDownList3" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource3" DataTextField="Job_Classification" DataValueField="Job_Classification" Height="17px" Width="384px"> 
    </asp:DropDownList> 
    <asp:ListView id="YourListView" OnLoad="YourListView_Load" runat="server" DataSourceID="SqlDataSource4"> 
     <ItemTemplate> 
      <span style="">Plant: 
      <asp:Label id="PlantLabel" runat="server" Text='<%# Eval("Plant") %>' /> 
      <br /> 
      column1: 
      <asp:Label id="column1Label" runat="server" Text='<%# Eval("column1") %>' /> 
      <br /> 
      Group: 
      <asp:Label id="GroupLabel" runat="server" Text='<%# Eval("Group") %>' /> 
      <br /> 
      Job_Code: 
      <asp:Label id="Job_CodeLabel" runat="server" Text='<%# Eval("Job_Code") %>' /> 
      <br /> 
      Job_Classification: 
      <asp:Label id="Job_ClassificationLabel" runat="server" Text='<%# Eval("Job_Classification") %>' /> 
      <br /> 
      Job_Function: 
      <asp:Label id="Job_FunctionLabel" runat="server" Text='<%# Eval("Job_Function") %>' /> 
      <br /> 
      Job_Description: 
      <asp:Label id="Job_DescriptionLabel" runat="server" Text='<%# Eval("Job_Description") %>' /> 
      <br /> 
      TWA: 
      <asp:Label id="TWALabel" runat="server" Text='<%# Eval("TWA") %>' /> 
      <br /> 
      <br /> 
      </span> 
     </ItemTemplate> 

     </asp:ListView> 
    <asp:SqlDataSource id="SqlDataSource4" runat="server" ConnectionString="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString %>" ProviderName="<%$ ConnectionStrings:2007 SoundAssist VER 1.0.5 05-12-2011 (2013-06-24)ConnectionString.ProviderName %>" SelectCommand="SELECT [Plant], [Group No#] AS column1, [Group], [Job Code] AS Job_Code, [Job Classification] AS Job_Classification, [Job Function] AS Job_Function, [Job Description] AS Job_Description, [TWA] FROM [Temp Table that contains TWA values] WHERE (([Plant] = ?) AND ([Group No#] = ?) AND ([Job Classification] = ?))"> 
     <SelectParameters> 
      <asp:ControlParameter ControlID="DropDownList1" Name="Plant" PropertyName="SelectedValue" Type="String" /> 
      <asp:ControlParameter ControlID="DropDownList2" Name="column1" PropertyName="SelectedValue" Type="String" /> 
      <asp:ControlParameter ControlID="DropDownList3" Name="Job_Classification" PropertyName="SelectedValue" Type="String" /> 
     </SelectParameters> 
    </asp:SqlDataSource>

当失败时'theTWALabel.Text'的值是多少？另外，你应该考虑'Int32.TryParse'，因为你正在从一个文本框中读取（这是不受限制的）？ – Brad

答

你有实际检查输入是有效的 - 我会用TryParse，而不是转换功能：

if (int.TryParse(theTWALabel.Text, out theTWAValue)) 
{ 
}

更新后的编辑

我可能是错的，但我不要认为Label控件的值会回传给服务器 - 这可以解释为什么它们显示为空。无论如何，从“已加载”事件设置颜色看起来不必要的复杂。为什么不创建一个辅助方法并直接绑定？

protected Color GetColorForLabel(string text) 
{ 
    int theTWAValue; 
    if (text != null && int.TryParse(text, out theTWAValue) && theTWAValue >= 0) 
    { 
     return (theTWAValue < 90) ? System.Drawing.Color.Yellow : System.Drawing.Color.Red; 
    } 
    return System.Drawing.Color.Green; 
}

然后用它的前景属性绑定：

<asp:Label id="TWALabel" runat="server" 
    Text = '<%# Eval("TWA") %>' 
    Foreground = '<%# GetColorForLabel(Eval("TWA") as string) %>' />

它现在运行，但不会改变颜色。是否因为我有用户在输出之前选择listview的参数？我的意思是，我让他们选择工厂名称，然后选择部门，然后选择工作分类，然后显示列表视图。 – friendo9876

@ friendo9876是的，似乎意味着价值没有得到回到服务器出于某种原因。没有足够的信息可以肯定地说。 – McGarnagle

你需要什么额外的信息，我可以添加到此页面以使答案更精确？ – friendo9876

答

您可以添加Trim function

theTWAValue=Convert.ToInt32(theTWALabel.Text.Trim());

MSDN链接：http://msdn.microsoft.com/fr-fr/library/vstudio/t97s7bs3.aspx

我建议你涂用Int32.TryParse function

链接：http://msdn.microsoft.com/fr-fr/library/vstudio/f02979c7.aspx

修剪功能到底是什么？ – friendo9876

抑制空白，因为“33”不是“33”（有空格） –

修剪将删除字符串的开头和结尾的空格，但我不认为这是你的问题 – Rab

答

试试这个

theTWAValue = Convert.ToInt32(theTWALabel.Text.ToString().Trim());

Trime without e sora –

刚刚编辑，对不起，我输入的太快：P – sora0419

好sora我加了点 –

答

如果您theTWALabel.Text值是空的，那么你会得到这个错误。在尝试转换之前检查里面是否有值。

列表视图不会显示，直到用户选择每个下拉列表中的项目，所以这是我的问题吗？ – friendo9876

我想你是通过与McGarnagle讨论来回答的，对吗？ –

雅现在工作 – friendo9876

答

使用int.TryParse代替。

int value; 
if(!int.TryParse(theTWALabel.Text, out value)) 
{ 
    //didn't parse right 
}

输入字符串格式不正确？

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