C# 字符串按设置的格试在前面或后面增加空格或其它字符

 public string lengadd(string stringa, string stringb, int count, int mode)  //以stringa的长度,未到count的长度则增加stringb,mode属性0是增加前面,1是增加后面
        {
            int stringaa = System.Text.Encoding.Default.GetBytes(stringa).Length;
            if (mode == 0)
            {
                for (int i = 1; i <= (count - stringaa); i++)
                {
                    stringa = stringb + stringa;
                }

            }
            else
            {
                for (int i = 1; i <= (count - stringaa); i++)
                {
                    stringa = stringa + stringb;
                }

            }
            return stringa;
        }