c# - 如何从双字节字符集中打印字符

Question

看看如何从可打印或不可打印的单字节字符集中输出所有字符。输出文件将包含日语字符，例如ﾁﾎﾔﾂｾ。

Encoding enc = Encoding.GetEncoding("shift_jis");
byte[] m_bytes = new  byte [1];
StreamWriter sw = new StreamWriter(@"C:\shift_jis.txt");

for (int i = 0; i < 256; i++)
{
    m_bytes.SetValue ((byte)i,0);
    String Output = enc.GetString(m_bytes);
    sw.WriteLine(Output);
}

sw.Close();
sw.Dispose();

这是我尝试使用双字节字符集执行此操作。

Encoding enc = Encoding.GetEncoding("iso-2022-jp");
byte[] m_bytes = new byte[2];
StreamWriter sw = new StreamWriter(@"C:\iso-2022-jp.txt");

for (int i = 0; i < 256; i++)
{
    m_bytes.SetValue((byte)i, 0);

    for (int j = 0; j < 256; j++)
    {
        m_bytes.SetValue((byte)j, 1);
        String Output = null;
        Output = enc.GetString(m_bytes);
        sw.WriteLine(Output);
    }
}

sw.Close();
sw.Dispose();

问题是输出文件仍然只包含前 255 个字符。每个字节都被单独评估，并分别返回该字节的字符。输出字符串总是包含两个字符而不是一个。由于字符集中的字符是用两个字节表示的，所以必须用两个字节来指定它们对吗？

那么如何遍历并打印双字节字符集中的所有字符呢？

Answer 1

如果可以按 unicode 顺序排列它们，您可以:

Encoding enc = (Encoding)Encoding.GetEncoding("iso-2022-jp").Clone();
enc.EncoderFallback = new EncoderReplacementFallback("");
char[] chars = new char[1];
byte[] bytes = new byte[16];

using (StreamWriter sw = new StreamWriter(@"C:\temp\iso-2022-jp.txt"))
{
    for (int i = 0; i <= char.MaxValue; i++)
    {
        chars[0] = (char)i;
        int count = enc.GetBytes(chars, 0, 1, bytes, 0);

        if (count != 0)
        {
            sw.WriteLine(chars[0]);
        }
    }
}

如果你想按字节顺序排序，你可以:

Encoding enc = (Encoding)Encoding.GetEncoding("iso-2022-jp").Clone();
enc.EncoderFallback = new EncoderReplacementFallback("");
char[] chars = new char[1];
byte[] bytes = new byte[16];

var lst = new List<Tuple<byte[], char>>();

for (int i = 0; i <= char.MaxValue; i++)
{
    chars[0] = (char)i;
    int count = enc.GetBytes(chars, 0, 1, bytes, 0);

    if (count != 0)
    {
        var bytes2 = new byte[count];
        Array.Copy(bytes, bytes2, count);
        lst.Add(Tuple.Create(bytes2, chars[0]));
    }
}

lst.Sort((x, y) =>
{
    int min = Math.Min(x.Item1.Length, y.Item1.Length);

    for (int i = 0; i < min; i++)
    {
        int cmp = x.Item1[i].CompareTo(y.Item1[i]);

        if (cmp != 0)
        {
            return cmp;
        }
    }

    return x.Item1.Length.CompareTo(y.Item1.Length);
});

using (StreamWriter sw = new StreamWriter(@"C:\temp\iso-2022-jp.txt"))
{
    foreach (var tuple in lst)
    {
        sw.WriteLine(tuple.Item2);

        // This will print the full byte sequence necessary to 
        // generate the char. Note that iso-2022-jp uses escape
        // sequences to "activate" subtables and to deactivate them.
        //sw.WriteLine("{0}: {1}", tuple.Item2, string.Join(",", tuple.Item1.Select(x => x.ToString("x2"))));
    }
}

或使用不同的排序顺序(长度优先):

lst.Sort((x, y) =>
{
    int cmp2 = x.Item1.Length.CompareTo(y.Item1.Length);

    if (cmp2 != 0)
    {
        return cmp2;
    }

    int min = Math.Min(x.Item1.Length, y.Item1.Length);

    for (int i = 0; i < min; i++)
    {
        int cmp = x.Item1[i].CompareTo(y.Item1[i]);

        if (cmp != 0)
        {
            return cmp;
        }
    }

    return 0;
});

请注意，在所有示例中，我只生成基本 BMP 平面的字符。我不认为基本 BMP 平面之外的字符包含在任何编码中...如果有必要，我可以修改代码以支持它。

出于好奇，处理非 BMP 字符(iso-2022-jp 中不存在)的第一个代码版本:

Encoding enc = (Encoding)Encoding.GetEncoding("iso-2022-jp").Clone();
enc.EncoderFallback = new EncoderReplacementFallback("");
byte[] bytes = new byte[16];

using (StreamWriter sw = new StreamWriter(@"C:\temp\iso-2022-jp.txt"))
{
    int max = -1;
    for (int i = 0; i <= 0x10FFFF; i++)
    {
        if (i >= 0xD800 && i <= 0xDFFF)
        {
            continue;
        }

        string chars = char.ConvertFromUtf32(i);

        int count = enc.GetBytes(chars, 0, chars.Length, bytes, 0);

        if (count != 0)
        {
            sw.WriteLine(chars);
            max = i;
        }
    }

    Console.WriteLine("maximum codepoint: {0}", max);
}