什么 .NET UnmanagedType 是 Unicode (UTF-16)？

发布于 2024-09-04 11:57:53 字数 847 浏览 6 评论 0原文

我将字节打包到一个结构中，其中一些对应于 Unicode 字符串。以下内容对于 ASCII 字符串效果很好：

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
    public string MyString;
}

我假设我可以

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.LPWStr, SizeConst = 32)]
    public string MyString;
}

将其设为 Unicode，但这不起作用（字段值为空，其他字段的值不正确，表明字节解包被搞乱了）。（由于该字段是具有其他字段的结构的一部分，为了清楚起见，我省略了这些字段，因此我不能简单地更改包含结构的 CharSet。）

知道我做错了什么吗？

这是输入（64 字节，小端）：

31:00:31:00:32:00:33:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00

输出应该是 Unicode 字符串“1123”。

原文

I am packing bytes into a struct, and some of them correspond to a Unicode string. The following works fine for an ASCII string:

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
    public string MyString;
}

I assumed that I could do

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.LPWStr, SizeConst = 32)]
    public string MyString;
}

to make it Unicode, but that didn't work (the field value was empty and the other fields had incorrect values, indicating that the byte unpacking was messed up). (Since this field is part of a struct with other fields, which I've omitted for clarity, I can't simply change the CharSet of the containing struct.)

Any idea what I'm doing wrong?

Here is the input (64 bytes, little endian):

31:00:31:00:32:00:33:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00

The output should be the Unicode string "1123".

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一张白纸 2024-09-11 11:57:53

我将通过声明字符串类型的嵌套结构来做到这一点。 “内部”结构可以声明其CharSet。这类似于我博客上的解决方案： http:// nitoprograms.blogspot.com/2010/02/interop-multiDimension-arrays-of.html

例如：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct StringSizeConst32AsString
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    private string Value;

    public static implicit operator string(StringSizeConst32AsString source)
    {
        return source.Value;
    }

    public static implicit operator StringSizeConst32AsString(string source)
    {
        // Note that longer strings would be silently truncated
        //  if we didn't explicitly check this.
        if (source.Length >= 32)
            throw new Exception("String too large for field: " + source);

        return new StringSizeConst32AsString { Value = source };
    }
}

I would do this by declaring a nested structure for the string type. The "inner" structure can declare its CharSet. This is similar to the solution on my blog: http://nitoprograms.blogspot.com/2010/02/interop-multidimensional-arrays-of.html

e.g.:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct StringSizeConst32AsString
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    private string Value;

    public static implicit operator string(StringSizeConst32AsString source)
    {
        return source.Value;
    }

    public static implicit operator StringSizeConst32AsString(string source)
    {
        // Note that longer strings would be silently truncated
        //  if we didn't explicitly check this.
        if (source.Length >= 32)
            throw new Exception("String too large for field: " + source);

        return new StringSizeConst32AsString { Value = source };
    }
}

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小忆控 2024-09-11 11:57:53

感谢@StephenCleary。我的完整解决方案是这样的：

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.Struct)]
    public UnicodeString MyString;
}

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
private struct UnicodeString
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    public string Value;

    public static implicit operator string(UnicodeString value)
    {
        return value.Value;
    }
}

Credit to @StephenCleary. My full solution is this:

[StructLayout(LayoutKind.Sequential)]
private struct PacketBytes
{
    [MarshalAs(UnmanagedType.Struct)]
    public UnicodeString MyString;
}

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
private struct UnicodeString
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    public string Value;

    public static implicit operator string(UnicodeString value)
    {
        return value.Value;
    }
}

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