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

Question

What I tried   MarkUP     lt asp TextBox ID  TextBox2    runat  server  gt  lt  asp TextBox gt        lt asp Label ID  Label1  runat  server  AssociatedControlID  TextBox2   Text  Label  gt  lt  asp Label gt        lt asp SliderExtender ID  SliderExtender1   TargetControlID  TextBox2   BoundControlID  Label1  Maximum  200  Minimum  100  runat  server  gt       lt  asp SliderExtender gt    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

User · Accepted Answer

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

User · Answer

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

User · Answer

Replace with   imageWidth   1   Convert ToInt32 Label1 Text

User · Answer

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

[c#] How to resolve "Input string was not in a correct format." error?

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