Converting String to Int C#

Question

I am trying to convert an inputted string to an int. I have tried int.parse, and int.parse32 but when I press "enter" I get the following error:

System.FormatException: Input string was not in a correct format.
  at System.Number.StringToNumber(String str, NumberStyles options, 
                                  NumberBuffer & number...."

partial class Form1:

this.orderID.Text = currentID;
this.orderID.KeyPress += new KeyPressEventHandler(EnterKey);

partial class Form1:Form:

  public int newCurrentID;
  private void EnterKey(object o, KeyPressEventArgs e)
    {
        if(e.KeyChar == (char)Keys.Enter)
        {
            try
            {
                newCurrentID = int.Parse(currentID);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
            e.Handled = true;
        }
    }

Put a break point to method EnterKey and see what currentID contains. — I4V
– I4V, Commented May 14, 2013 at 7:11
Are you relying on the fact that you set currentID at the top of the class? This wont pick up changes to currentID and will/may be empty when the form loads. Try getting the value from the control directly; for example, Int.TryParse(orderID.Text, out someInt); — dash
– dash, Commented May 14, 2013 at 7:14
You don't show code where the value of orderID.Text is copied into currentID. You do have that, don't you? — Hans Keﬆing
– Hans Keﬆing, Commented May 14, 2013 at 7:16

Magnus · Accepted Answer · 2013-05-14 07:24:47Z

4

String is immutable so when you assign currentID to the textbox any changes of that text will not be reflected in the variable currentID

this.orderID.Text = currentID;

What you need to do in the EnterKey function is to use the Textbox value directly:

private void EnterKey(object o, KeyPressEventArgs e)
{
        if(e.KeyChar == (char)Keys.Enter)
        { 
            if(!int.TryParse(orderID.Text, out newCurrentID))
               MessageBox.Show("Not a number");
            e.Handled = true;
        }
 }

answered May 14, 2013 at 7:24

Magnus

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1 Comment

Alex Moreno Over a year ago

Thanks, this helped me out alot, and taught me a new thing as well. :)

Hikiko · Accepted Answer · 2013-05-14 07:12:13Z

4

Check string for string.IsNullOrEmpty() and do not try to parse such strings.

answered May 14, 2013 at 7:12

Hikiko

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1 Comment

Destrictor Over a year ago

I'd like to mention the newer string.IsNullOrWhitespace() method (since C# 4.0), does some extra checking for the user :).

Kai · Accepted Answer · 2013-05-14 07:14:42Z

1

Use TryParse instead of parse the value directly:

int intResult = 0;

if (Int32.TryParse(yourString, out intResult) == true)
{
    // do whatever you want...
}

answered May 14, 2013 at 7:14

Kai

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Comments

Neeraj · Accepted Answer · 2013-05-14 07:16:26Z

0

Try This Code

if (!string.IsNullOrEmpty(currentID)){
     newCurrentID = int.Parse(currentID);
}

answered May 14, 2013 at 7:16

Neeraj

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