Textbox validation for amount

I want to check a textbox value where value have to positive or negative.. negative input value should -10.25, -0.20,-6 etc these patern. and also positive input value should 1.25, 0.50, 5 etc these patarn. I want to validate onKeyPress Event..

Did you try like this:

You nned to attach an keypress event in textbox properties.

http://csharp.net-informations.com/gui/key-press-cs.htm

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsControl(e.KeyChar) && (!char.IsDigit(e.KeyChar))
&& (e.KeyChar != '.') && (e.KeyChar != '-'))
e.Handled = true;
// only allow one decimal point
if (e.KeyChar == '.' && (sender as TextBox).Text.IndexOf('.') > -1)
e.Handled = true;
// only allow minus sign at the beginning
if (e.KeyChar == '-' && (sender as TextBox).Text.Length > 0)
e.Handled = true;
if (e.KeyChar == 13 || e.KeyChar == (char)Keys.Enter)
{
try
{
double myDouble = double.parse(TextBox1.Text)
}
catch (Exception e)
{
MessageBox.Show("Input is incorrect", "Error");
// make textBox1 blank and red as border..
TextBox1.Text = "";
}
}
// OR try like this
var regex = new Regex("^[-]?\d+(\.\d+)?$", RegexOptions.Compiled);
Match m = regex.Match(TextBox1.Text + e.KeyChar);
if(!m.Success)
{
MessageBox.Show("Input is incorrect", "Error");
}
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Manas Mohapatra9y ago
Did you try like this:

You nned to attach an keypress event in textbox properties.

http://csharp.net-informations.com/gui/key-press-cs.htm
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{

    if (!char.IsControl(e.KeyChar) && (!char.IsDigit(e.KeyChar))
        && (e.KeyChar != '.')  && (e.KeyChar != '-'))
        e.Handled = true;

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

    // only allow minus sign at the beginning
    if (e.KeyChar == '-' && (sender as TextBox).Text.Length > 0)
        e.Handled = true;

    if (e.KeyChar == 13 || e.KeyChar == (char)Keys.Enter)
    {
        try
        {
            double myDouble = double.parse(TextBox1.Text)
        }
        catch (Exception e)
        {
            MessageBox.Show("Input is incorrect", "Error");

            // make textBox1 blank and red as border..
            TextBox1.Text = "";
        }
    }

    // OR try like this
    var regex = new Regex("^[-]?\d+(\.\d+)?$", RegexOptions.Compiled);
    Match m = regex.Match(TextBox1.Text + e.KeyChar);
    if(!m.Success)
    {
        MessageBox.Show("Input is incorrect", "Error");
    }

}