[英]Byte array to struct
I'm having trouble converting the string parts of the byte array. 我在转换字节数组的字符串部分时遇到问题。
My struct looks like this: 我的结构看起来像这样:
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct Message
{
public int id;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
public string text;
}
Creation of test byte array: 创建测试字节数组:
private static byte[] CreateMessageByteArray()
{
int id = 69;
byte[] intBytes = BitConverter.GetBytes(id);
string text = "test";
byte[] stringBytes = GetBytes(text);
IEnumerable<byte> rv = intBytes.Concat(stringBytes);
return rv.ToArray();
}
Method to convert my bytearray to a struct: 将我的bytearray转换为结构的方法:
static T ByteArrayToStructure<T>(byte[] bytes) where T : struct
{
var handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
var result = (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(T));
handle.Free();
return result;
}
When I call ByteArrayToStructure
with the result from CreateMessageByteArray()
I get a struct with an id=60 and text="t". 当我使用CreateMessageByteArray()
的结果调用ByteArrayToStructure
,我得到一个id = 60和text =“t”的结构。
Why don't I get the whole string eg "test" ? 为什么我没有得到整个字符串,例如“test”?
Edit: This is the code I forgot to pase: 编辑:这是我忘记编码的代码:
static byte[] GetBytes(string str)
{
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
The problem is at this line: 问题出在这一行:
byte[] stringBytes = GetBytes(text);
How are you converting the string to a byte array? 你是如何将字符串转换为字节数组的? You are probably using a Unicode encoding, which will store each character as two bytes, and because your string is in the ASCII set, every other byte will be zero: 您可能正在使用Unicode编码,它将每个字符存储为两个字节,并且因为您的字符串是ASCII集,所以每隔一个字节将为零:
byte[] stringBytes = new UnicodeEncoding().GetBytes(text);
// will give you { 't', '\0', 'e', '\0', 's', '\0', 't', '\0' }
These zeroes mislead the marshalling mechanism into assuming they are terminal characters and so the string ends just after the 't'
. 这些零错误地将编组机制误认为它们是终端字符,因此字符串在't'
之后结束。
Instead, you can use an ASCII encoding (which stores one byte per character): 相反,您可以使用ASCII编码(每个字符存储一个字节):
byte[] stringBytes = new ASCIIEncoding().GetBytes(text);
// will give you { 't', 'e', 's', 't' }
// but will lose non-ASCII character information
Or you can use a UTF8 encoding (which is variable length): 或者您可以使用UTF8编码(可变长度):
byte[] stringBytes = new UTF8Encoding().GetBytes(text);
// will give you { 't', 'e', 's', 't' }
// and retain non-ASCII character information, but it's somewhat
// trickier to rebuild the string correctly in case of non-ASCII
// information present
除了其他两个答案之外,如果您希望text
字段中的字符串始终为Unicode,则可以在[StructLayout]
属性中包含CharSet = CharSet.Unicode
Maybe GetBytes method doesn't work as you expect. 也许GetBytes方法不能按预期工作。 This linqpad works fine for me: 这个linqpad对我来说很好:
void Main()
{
var result = ByteArrayToStructure<Message>(CreateMessageByteArray());
result.Dump();
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct Message
{
public int id;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
public string text;
}
private static byte[] CreateMessageByteArray()
{
int id = 69;
byte[] intBytes = BitConverter.GetBytes(id);
string text = "test";
byte[] stringBytes = Encoding.UTF8.GetBytes(text);
IEnumerable<byte> rv = intBytes.Concat(stringBytes);
return rv.ToArray();
}
static T ByteArrayToStructure<T>(byte[] bytes) where T : struct
{
var handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
var result = (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(T));
handle.Free();
return result;
}
Output: 输出:
id 69
text test
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