textbox validation for allow one “ . ” value c#

Question

I want textbox validation for allowing only one . value and only numbers. Means my textbox value should take only numerics and one . value. Value shoul

Answer 1

Also try this short one

e.Handled = (!(e.KeyChar == (char)Keys.Back || e.KeyChar == '.')); //allow  dot and Backspace
e.Handled = (e.KeyChar == '.' && TextBox1.Text.Contains(".")); //allow only one dot

this example only allow one dot and backspace

Answer 2

 if (textBox.Text!="")
        {
            string txt = textBox.Text;
            if (e.KeyChar.ToString().Any(Char.IsNumber) || e.KeyChar == '.')
            {
                textBox.Text = rate;
            }
            else
            {
                MessageBox.Show("Number Only", "Warning");
                textBox.Text = "";
            }
        }

My tested code

Answer 3

try this one

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!char.IsControl(e.KeyChar)
               && !char.IsDigit(e.KeyChar)
               && e.KeyChar != '.')
            e.Handled = true;

        // only allow one decimal point
        if (e.KeyChar == '.'
            && textBox1.Text.IndexOf('.') > -1)
            e.Handled = true;
    }

Answer 4

try this code and just replace what you want input type 'validinpu' string.

try
{
    short charCode = (short)Strings.Asc(e.KeyChar);
    string validinput = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-0123456789 .";
    if (Strings.InStr(validamt, Conversions.ToString(Strings.Chr(charCode)), Microsoft.VisualBasic.CompareMethod.Binary) == 0)
    {
        charCode = 0;
    }
    if (charCode == 0)
    {
        e.Handled = true;
    }
}

Answer 5

if(e.KeyChar.Equals('\b'))
 {
  e.Handled = false;
 }
else
 if (!char.IsControl(e.KeyChar)
           && !char.IsDigit(e.KeyChar)
           && e.KeyChar != '.')
  {
        e.Handled = true;
  }
 else
    // only allow one decimal point
    if (e.KeyChar == '.'
        && textBox1.Text.IndexOf('.') > -1)
  {        
    e.Handled = true;  
  }

Answer 6

Another example ,

 private void txtPrice_KeyPress(object sender, KeyPressEventArgs e)
    {
         // To disallow typing in the beginning writing
        if (txtPrice.Text.Length == 0)
        {
            if (e.KeyChar == '.')
            {
                e.Handled = true;
            }
        }
        if (!char.IsDigit(e.KeyChar) && e.KeyChar != 8 && e.KeyChar != 46)
        {
            e.Handled = true;
        }
        if (e.KeyChar == '.' && txtPrice.Text.IndexOf('.') > -1)
        {
            e.Handled = true;
        }
    }