文本框的正则表达式

Question

I am trying to remove the last entered letter in a texbox. I am using a Regex to determine if the entry is valid. However, the code I have only checks the first character, and stops after that. Not sure what I am doing wrong.

I want the user to be able to input as many numbers as they want (including negative numbers).

Here is my code:

private void textBox_Gen_Offset_TextChanged(object sender, EventArgs e)
{
    Regex pattern = new Regex("[-+]?[0-9]*");

    if (pattern.IsMatch(textBox_Gen_Offset.Text))
    {
        UpdateTotal();
    }
    else
    {
        if (textBox_Gen_Offset.Text.Length > 0)
        {
            textBox_Gen_Offset.Text = textBox_Gen_Offset.Text.Substring(0, textBox_Gen_Offset.Text.Length - 1);
        }
    }
}

Answer 1

I'm not an expert on regex, but you could check if entered data is numeric by trying to parse is as an int or a double (for integers or floating point numbers respectively).

        int intInTheBox;
        if (int.TryParse(textBox_Gen_Offset.Text, out intInTheBox))
        {
            //Do stuff if it's an int
        }

        double doubleInTheBox;
        if (double.TryParse(textBox_Gen_Offset.Text, out doubleInTheBox))
        {
            //Do stuff if it's a double
        }