如果我在C＃的文本框中以小数点开始输入，则会出现输入格式异常

Question

I'm calculating Fabric Weight in Decimal.

If I enter 0.071, the program works fine. but if I enter .071 I get input format exception error which is dumb. I want to remove this irritating input format exception error, because a user forgot to enter 0.071.

here are the details.

• Screenshot of my Fabric Weight Textbox with decimal point in it

• Exception I'm getting.

    try { if (System.Text.RegularExpressions.Regex.IsMatch(textBox28.Text, "[^0-9^+]")) { MessageBox.Show("Please enter only numbers."); textBox28.Clear(); textBox28.Focus(); } } catch (ArgumentOutOfRangeException err){ MessageBox.Show(err.ToString()); } try { // Input format error 702 FabricWeight = float.Parse(textBox28.Text); } catch (FormatException err) { MessageBox.Show(err.ToString()); 

Answer 1

Before FabricWeight = float.Parse(textBox28.Text); you could add:

if(textBox28.Text.StartsWith('.')
{
      textBox28.Text = string.Format("{0}{1}", 0, textBox28.Text);
}

And as Jon said - using TryParse is way more efficient.

Answer 2

Try this code in event key-press of textbox, its better way:

private void textBox28_KeyPress(object sender, KeyPressEventArgs e)
    {
        if ( System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), "[^0-9^+.]") )
            e.Handled = true;
        if (e.KeyChar == '.' && textBox28.Text.Length == 0)
            e.Handled = true;

        int i = 0;
        foreach (char cc in textBox28.Text)
            if (cc == '.')
                i++;
        if (i >= 1 && e.KeyChar == '.')
            e.Handled = true;
    }

I test it now. please check this.

Answer 3

Credits to @ Bruniasty

This works.

"Below this method" I'm storing result in Fabric Weight, you can use this for your program and store to any variable you like after "Try Parsing".

    private static void TryToParse(string value)
    {
        double number;
        bool result = double.TryParse(value, out number);

        if (result)
        {

            FabricWeight = number;

        }
        else
        {
            if (value == null) value = "";

        }
    }

Wrote this and worked.

TryToParse(textBox28.Text);

for more information: Visit this link MSDN Library: TryParse