how to allow textbox to acccept only numbers and decimal point?

i want to enter price value in my textbox.i want it to accept only numbers and one decimal point.right now its taking only numbers but not decimal point.the code i hav written is given below bt its only to accept numbers not decimal point.
 string s = txtPrice.Text;
            int chars = s.Length;
           // char p = '.';
            for (int i = 0; i < chars; i++)
            {
                if (!char.IsNumber(s, i))
                {                
                        MessageBox.Show("Enter only numbers");
                        txtPrice.Text = s.Remove(i, 1);
                        txtPrice.Select(txtPrice.Text.Length, 0);
                        return;                  
                }Start Free Trial