HOWTO: 判断全角和半角

ASCII码大于255，则为双字节？

另外查看MSDN中KeyPress事件

1,FCL

System.Text.UnicodeEncoding.Unicode.GetByteCoun(str)

试验无效。全部返回2，又试验ASCIIEncoding.ASCII类的同名方法，全部返回1

2,Regex

全角：[^\x00-\xff]

3,第三方实现

   1:  #region 半全角互换

   2:  /// <summary>

   3:  /// 转全角的函数(SBC case)

   4:  /// </summary>

   5:  /// <param name="input">任意字符串</param>

   6:  /// <returns>全角字符串</returns>

   7:  ///<remarks>

   8:  ///全角空格为12288，半角空格为32

9: ///其他字符半角(33-126)与全角(65281-65374)的对应关系是：均相差65248

  10:  ///</remarks>        

  11:  public static string ToSBC(string input)

  12:  {

  13:      //半角转全角：

  14:      char[] c = input.ToCharArray();

  15:      for (int i = 0; i < c.Length; i++)

  16:      {

  17:          if (c[i] == 32)

  18:          {

  19:              c[i] = (char)12288;

  20:              continue;

  21:          }

  22:          if (c[i] < 127 && c[i] > 32)

  23:          {

  24:              c[i] = (char)(c[i] + 65248);

  25:          }

  26:      }

  27:      return new string(c);

  28:  }

  29:   

  30:  /// <summary>

  31:  /// 转半角的函数(DBC case)

  32:  /// </summary>

  33:  /// <param name="input">任意字符串</param>

  34:  /// <returns>半角字符串</returns>

  35:  ///<remarks>

  36:  ///全角空格为12288，半角空格为32(此处不必转空格)

37: ///其他字符半角(33-126)与全角(65281-65374)的对应关系是：均相差65248

  38:  ///</remarks>

  39:  public static string ToDBC(string input)

  40:  {

  41:      char[] c = input.ToCharArray();

  42:      for (int i = 0; i < c.Length; i++)

  43:      {

  44:          if (c[i] == 12288)

  45:          {

  46:              c[i] = (char)32;

  47:              continue;

  48:          }

  49:          if (c[i] > 65280 && c[i] < 65375)

  50:          {

  51:              c[i] = (char)(c[i] - 65248);

  52:          }

  53:      }

  54:      return new string(c);

  55:  }

  56:  #endregion