IP地址的字段验证-FieldValidationForAnIPAddress

I am trying to prevent a user from entering anything into a particular textbox aside from a number or a period in C#. The textbox is supposed to contain an IP address. I have it working such that non-numeric entries are prevented, however I can't seem to get it to allow a period to be entered. How might I accomplish this?

我试图阻止用户在C#中的数字或句点之外输入特定文本框中的任何内容。文本框应包含IP地址。我有它的工作,以防止非数字条目,但我似乎无法让它允许输入一个句号。我怎么能做到这一点?

    private void TargetIP_KeyDown(object sender, KeyEventArgs e)
    {
        // Initialize the flag to false.
        nOnNumberEntered= false;

        // Determine whether the keystroke is a number from the top of the keyboard.
        if (e.KeyCode  Keys.D9)
        {
            // Determine whether the keystroke is a number from the keypad.
            if (e.KeyCode  Keys.NumPad9)
            {
                // Determine whether the keystroke is a backspace.
                if (e.KeyCode != Keys.Back)
                {
                    nOnNumberEntered= true;
                    errorProvider1.SetError(TargetIP, FieldValidationNumbersOnly);
                    // A non-numerical keystroke was pressed.
                    // Set the flag to true and evaluate in KeyPress event.
                }
            }
        }

        //If shift key was pressed, it's not a number.
        if (Control.ModifierKeys == Keys.Shift)
        {
            nOnNumberEntered= true;
        }
    }


    private void TargetIP_KeyPress(object sender, KeyPressEventArgs e)
    {
        // Check for the flag being set in the KeyDown event.
        if (nOnNumberEntered== true)
        {
            // Stop the character from being entered into the control since it is non-numerical.
            e.Handled = true;
        } 

        else
        {
            errorProvider1.Clear();
        }
    }

1 个解决方案