字符串转int值

static int StrToInt(string str, int defValue)
        {
            if (str == null)
                return defValue;
            if (str.Length > 0 && str.Length <= 11 && Regex.IsMatch(str, @"^[-]?[0-9]*$"))
            {
                if ((str.Length < 10) || (str.Length == 10 && str[0] == '1') || (str.Length == 11 && str[0] == '-' && str[1] == '1'))
                {
                    return Convert.ToInt32(str);
                }
            }
            return defValue;      
        }