求这个正则的修改,该如何解决

求这个正则的修改

C# code

if (!System.Text.RegularExpressions.Regex.IsMatch((sender as TextBox).Text, @"^(?!0\d)\d+(\.\d*)?$"))            {                int index = (sender as TextBox).SelectionStart;                (sender as TextBox).Text = (sender as TextBox).Tag as string;                (sender as TextBox).SelectionStart = index;            }

C# code

@"^(?!0\d)\d+$"