How to resolve "Input string was not in a correct format." error?

Question

What I tried:

MarkUP:

 <asp:TextBox ID="TextBox2"   runat="server"></asp:TextBox>

    <asp:Label ID="Label1" runat="server" AssociatedControlID="TextBox2"  Text="Label"></asp:Label>

    <asp:SliderExtender ID="SliderExtender1"  TargetControlID="TextBox2"  BoundControlID="Label1" Maximum="200" Minimum="100" runat="server">
    </asp:SliderExtender>

Code Behind:

protected void setImageWidth()
{
    int imageWidth;
    if (Label1.Text != null)
    {
        imageWidth = 1 * Convert.ToInt32(Label1.Text);
        Image1.Width = imageWidth;
    }
}

After running the page on a browser, I get the System.FormatException: Input string was not in a correct format.

Change `Convert.ToInt32(Label1.Text)` to `Convert.ToInt32(TextBox2.Text)` — Andre Calil, Sep 04 '12 at 18:23
What are you using for your Slider? Telerik, AjaxControlToolKit, something else? Find out where your result should be read from. The exception is telling you that the contents of Label1.Text can't be converted into an Int32. — Kevin, Sep 04 '12 at 19:46
@Kevin I am using AjaxControlToolkit and my result should come from Label1 — Md. Arafat Al Mahmud, Sep 05 '12 at 12:29

score 17 · Accepted Answer · edited Nov 27 '20 at 11:45

17

The problem is with line

imageWidth = 1 * Convert.ToInt32(Label1.Text);

Label1.Text may or may not be int. Check.

Use Int32.TryParse(value, out number) instead. That will solve your problem.

int imageWidth;
if(Int32.TryParse(Label1.Text, out imageWidth))
{
    Image1.Width= imageWidth;
}

edited Nov 27 '20 at 11:45

Osama Rizwan

615
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answered Sep 04 '12 at 18:30

Deval Ringwala

348
1
5

This error message could be thrown when try to Convert.ToDouble input comming from user with different cultureinfo, so you could use Convert.ToDouble (String, IFormatProvider) instead of just Convert.ToDouble (String). It is hard to debug, because program will work on you system, but will throw error on some of its users, this is why I have a method to log errors on my server and I found out for the problem fastly. – vinsa Apr 07 '18 at 14:24

score 3 · Answer 2 · edited May 03 '17 at 08:48

If using TextBox2.Text as the source for a numeric value, it must first be checked to see if a value exists, and then converted to integer.

If the text box is blank when Convert.ToInt32 is called, you will receive the System.FormatException. Suggest trying:

protected void SetImageWidth()
{
   try{
      Image1.Width = Convert.ToInt32(TextBox1.Text);
   }
   catch(System.FormatException)
   {
      Image1.Width = 100; // or other default value as appropriate in context.
   }
}

score 0 · Answer 3 · answered Sep 04 '12 at 18:23

0

Because Label1.Text is holding Label which can't be parsed into integer, you need to convert the associated textbox's text to integer

imageWidth = 1 * Convert.ToInt32(TextBox2.Text);

answered Sep 04 '12 at 18:23

Habib

219,104
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I just tried and still got the same error – Md. Arafat Al Mahmud Sep 04 '12 at 18:26
1

put a break point and see what is inside TextBox2.Text – Habib Sep 04 '12 at 18:28

score 0 · Answer 4 · answered Sep 04 '12 at 18:32

0

Replace with

imageWidth = 1 * Convert.ToInt32(Label1.Text);

answered Sep 04 '12 at 18:32

Aghilas Yakoub

28,516
5
46
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How to resolve "Input string was not in a correct format." error?

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