半角专全角，全角专半角 --c# asp.net 2.0

 /**//// <summary>
        /// 半角转全角
        /// </summary>
        /// <param name="BJstr"></param>
        /// <returns></returns>
        static public string GetQuanJiao(string BJstr)
        ...{
            ...#region
            char[] c = BJstr.ToCharArray();
            for (int i = 0; i < c.Length; i++)
            ...{
                byte[] b = System.Text.Encoding.Unicode.GetBytes(c, i, 1);
                if (b.Length == 2)
                ...{
                    if (b[1] == 0)
                    ...{
                        b[0] = (byte)(b[0] - 32);
                        b[1] = 255;
                        c[i] = System.Text.Encoding.Unicode.GetChars(b)[0];
                    }
                }
            }

            string strNew = new string(c);
            return strNew;

            #endregion
        }

        /**//// <summary>
        /// 全角转半角
        /// </summary>
        /// <param name="QJstr"></param>
        /// <returns></returns>
        static public string GetBanJiao(string QJstr)
        ...{
            ...#region
            char[] c = QJstr.ToCharArray();
            for (int i = 0; i < c.Length; i++)
            ...{
                byte[] b = System.Text.Encoding.Unicode.GetBytes(c, i, 1);
                if (b.Length == 2)
                ...{
                    if (b[1] == 255)
                    ...{
                        b[0] = (byte)(b[0] + 32);
                        b[1] = 0;
                        c[i] = System.Text.Encoding.Unicode.GetChars(b)[0];
                    }
                }
            }
            string strNew = new string(c);
            return strNew;
            #endregion
        }

  3、关于全角转半角的问题，在Unicode中，标点、数字、字母的半角编码最高位均为0，它们的全角编码与半角编码的第三位相差32h。