我正在将delphi
程序转换为c#
,我必须将二进制文件中的数据读入struct
。我在此问到的上一个问题回答了一种方法:Proper struct layout from delphi packed record。
然而,当尝试使用我拥有的另一个结构复制它时,这很有效,即使文件中实际存在数据,所有数据都是0。该文件是根据这些结构(或delphi版本中的打包记录)编写的,这个特定的代码应该迭代到文件中的最后一个'struct',并将其读入。我是将列出delphi和c#代码。
的Delphi:
CONST
RecordSize=128;
HeaderSize=128;
Testrec = packed record
now: TDateTime;
ShLat: longint;
ShLong: longint;
ShLatUn: short;
ShLonUn: short;
ShSens1: short;
ShSens2: short;
ShAlt: single;
ShFirst: single;
ShDepth: single;
ShSpeed: single;
ShHead: single;
ShCourse: single;
ShRoll: single;
ShPitch: single;
ShVOS: single;
FiLat: longint;
FiLong: longint;
FiLatUn: short;
FiLonUn: short;
FiSens1: short;
FiSens2: short;
FiAlt: single;
FiFirst: single;
FiDepth: single;
FiSpeed: single;
FiHead: single;
FiCourse: single;
FiRoll: single;
FiPitch: single;
FiVOS: single;
DataFlags: longint;
RevFlags: longint;
Contact: longint;
Range1: short;
Range2: short;
end;
var
RampStream:TFileStream;
Function GetLastTime:TDateTime;
var
RRampRec:TestRec;
LastPosition:TDateTime;
HoldPosition:Int64;
begin
LastPosition:=0;
HoldPosition:= RampStream.Position;
RampStream.Position:=128;
While RampStream.Position < RampStream.Size do
begin
RampStream.Read(RRampRec,RecordSize);
if (RRampRec.ShLat = 0) AND (RRampRec.ShLon = 0) AND
(RRampRec.FiLat = 0) AND (RRampRec.FiLon = 0) then continue;
LastPosition:= RRampRec.Now;
end;
RampStream.Position:=HoldPosition;
GetLastTime:=Lastposition;
end;
C#:
const int RecordSize = 128;
const int HeaderSize = 128;
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Testrec
{
public double now;
public int ShLat;
public int ShLon;
public short ShLat;
public short ShLon;
public short ShSens1;
public short ShSens2;
public float ShAlt;
public float ShFirst;
public float ShDepth;
public float ShSpeed;
public float ShHead;
public float ShCourse;
public float ShRoll;
public float ShPitch;
public float ShVOS;
public int FiLat;
public int FiLon;
public short FhLatUn;
public short FhLonUn;
public short FhSens1;
public short FhSens2;
public float FhAlt;
public float FhFirst;
public float FhDepth;
public float FhSpeed;
public float FhHead;
public float FhCourse;
public float FhRoll;
public float FhPitch;
public float FhVOS;
public int DataFlags;
public int RevFlags;
public int Contact;
public short Range1;
public short Range2;
}
FileStream RampStream;
private Double GetLastTime()
{
Testrec RRampRec = new Testrec();
double LastPosition;
long HoldPosition;
LastPosition = 0;
HoldPosition = RampStream.Position;
RampStream.Position = 128;
while (RampStream.Position < RampStream.Length)
{
RRampRec = ReadRecFromStream2(RampStream);
if ((RRampRec.ShLat == 0) && (RRampRec.ShLong == 0) && (RRampRec.FiLat == 0) && (RRampRec.FiLon == 0))
{
LastPosition = RRampRec.now;
}
}
RampStream.Position = HoldPosition;
return LastPosition;
}
TestrecReadRecFromStream2(Stream stream)
{
byte[] buffer = new byte[Marshal.SizeOf(typeof(Testrec))];
stream.Read(buffer, 0, HeaderSize);
GCHandle handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
try
{
return (Testrec)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(Testrec));
}
finally
{
handle.Free();
}
}
注意:流在前一个结构(即文件的第一个结构)中读取时已位于第128位。所以RampStream.Position = 128
开始这些功能时。
知道这里可能出现什么问题吗?我可以验证流的位置一次正确地上升128个字节。另外,我可以在RampStream.Position
的末尾验证RampStream.Length
是否等于while loop
。
答案 0 :(得分:2)
Delphi代码的缩进似乎让您感到困惑。它应该像这样缩进:
while RampStream.Position < RampStream.Size do
begin
RampStream.Read(RRampRec,RecordSize);
if (RRampRec.ShLat = 0) and (RRampRec.ShLon = 0)
and (RRampRec.FiLat = 0) and (RRampRec.FiLon = 0) then
continue;
LastPosition := RRampRec.Now;
end;
因此,LastPosition
仅在if
条件为假时分配。 LastPosition
条件为真时,您的C#代码会分配if
。要使C#代码匹配,您可以写:
while (RampStream.Position < RampStream.Length)
{
RRampRec = ReadRecFromStream2(RampStream);
if ((RRampRec.ShLat == 0) && (RRampRec.ShLong == 0)
&& (RRampRec.FiLat == 0) && (RRampRec.FiLon == 0))
continue;
LastPosition = RRampRec.now;
}
如果是我,虽然我会避免使用continue
并写下这样的样子:
while (RampStream.Position < RampStream.Length)
{
RRampRec = ReadRecFromStream2(RampStream);
if ((RRampRec.ShLat != 0) || (RRampRec.ShLong != 0)
|| (RRampRec.FiLat != 0) || (RRampRec.FiLon != 0))
LastPosition = RRampRec.now;
}
我总是对单个/复合语句感到紧张所以我可能会添加大括号:
while (RampStream.Position < RampStream.Length)
{
RRampRec = ReadRecFromStream2(RampStream);
if ((RRampRec.ShLat != 0) || (RRampRec.ShLong != 0)
|| (RRampRec.FiLat != 0) || (RRampRec.FiLon != 0))
{
LastPosition = RRampRec.now;
}
}