Input string was not in correct format?

Question

When I run my C# code, I get this error: Input string was not in a correct format. and it highlights this code:

       theTWAValue=Convert.ToInt32(theTWALabel.Text);

why is that happening?

Additional info:

The entire C# function:

    <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>

Here is the rest of the code:

<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>

what is the value of theTWALabel.Text when this fails? also, you should consider Int32.TryParse because you are reading from a textbox (which is not constrained otherwise?) — Brad
– Brad, Commented Jul 17, 2013 at 17:29

Jafar Kofahi · Accepted Answer · 2013-07-17 17:29:24Z

3

if your theTWALabel.Text value is empty then you would get this error. Check that there is a value inside before trying to convert.

answered Jul 17, 2013 at 17:29

Jafar Kofahi

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2 Comments

friendo9876 Over a year ago

the list view is not going to be displayed until the user selects the items in each drop down list, so is that my issue?

Jafar Kofahi Over a year ago

I guess u got ur answer from discussing with McGarnagle, am I right?

McGarnagle · Accepted Answer · 2013-07-17 19:47:41Z

2

You have to actually check that the input is valid -- I would use TryParse instead of the Convert function:

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

Update post-edit

I could be wrong, but I don't think the values of Label controls get posted back to the server -- this would explain why they're showing up as empty. In any case, setting colors from the "Loaded" event seems unnecessarily complicated. Why not create a helper method and bind it directly?

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;
}

Then use it to bind the Foreground property:

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

edited Jul 17, 2013 at 19:47

answered Jul 17, 2013 at 17:30

McGarnagle

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9 Comments

friendo9876 Over a year ago

Well it runs now but doesn't change the colors. Is it because I have the user select the parameters of the listview before it output? And by that I mean, I have them select the plant name, then the department, then the job classification, then it shows the list view.

McGarnagle Over a year ago

@friendo9876 Yeah, seems to imply that the value isn't getting posted back to the server for some reason. Not really enough info to say for sure.

friendo9876 Over a year ago

What additional information do you need that I can add to this page to make answer more precise?

McGarnagle Over a year ago

@friendo9876 the relevant parts of the markup would be helpful.

friendo9876 Over a year ago

when I run it i get this error: CS0246: The type or namespace name 'Color' could not be found (are you missing a using directive or an assembly reference?) and highlights this text : protected Color GetColorForLabel(string text)

|

Aghilas Yakoub · Accepted Answer · 2013-07-17 17:28:17Z

1

You can add Trim function

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

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

I suggest you tu use Int32.TryParse function

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

answered Jul 17, 2013 at 17:28

Aghilas Yakoub

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4 Comments

friendo9876 Over a year ago

What exactly does the Trim Function do?

Aghilas Yakoub Over a year ago

Suppress blank, because "33" is not "33 " (with space)

Rab Khan Over a year ago

trim will remove the white spaces in start and end of the string but I dont think that is your problem

Aghilas Yakoub Over a year ago

it's possible solution Rab Nawaz, if you don't have surface validation

sora0419 · Accepted Answer · 2013-07-17 17:28:49Z

1

try this

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

answered Jul 17, 2013 at 17:28

sora0419

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Comments

user1132959 · Accepted Answer · 2013-07-17 17:31:05Z

1

Use int.TryParse instead.

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

answered Jul 17, 2013 at 17:31

user1132959

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