无法从FILETIME（Windows时间）转换为dateTime（我收到不同的日期） [英] not being able to convert from FILETIME (windows time) to dateTime ( I get a different date )

问题描述

  //最好的工作的时间
 private static DateTime convertToDateTime（System.Runtime.InteropServices.ComTypes.FILETIME time）
 {
 long highBits = time.dwHighDateTime; 
 highBits = highBits<<< 32; 
返回DateTime.FromFileTimeUtc（highBits + time.dwLowDateTime）; 
} 
  

这里我在visual studio中有一个例子来显示这种方法有时不会例如，我将显示我的电脑中的实际文件和调试。所以碰巧在我调试中的文件是：

A：\Users\Tono\Documents\Visual Studio 2010 \Projects\WpfApplication4 \WpfApplication4\obj\x86\Debug\App.g.cs

这里是我要转换为DateTime的FILETIME我需要LastWriteTime

这里你可以看到dwHighDateTime = 30136437，还有那个dwLowDateTime = -2138979250从那个文件。

当我运行我的方法加其他技术我得到以下日期：

所以到目前为止，一切似乎都很好。但是为什么当我浏览并在Windows中查找特定的文件时，我得到一个不同的日期！这是查看文件属性时获取的日期：

为什么日期不匹配？我究竟做错了什么？

解决方案

您需要按位组合LS和MS值，而不是算术。

尝试：

  ulong high = 30136437; 
 unchecked 
 {
 int low = -2138979250; 
 uint uLow =（uint）low; 
 high = high<<< 32; 
 Date dt = DateTime.FromFileTime（（long）（high |（ulong）uLow））; 
} 
  

或以下任何一项也可以：

  long highBits = time.dwHighDateTime; 
 highBits = highBits<<< 32; 
 
返回DateTime.FromFileTimeUtc（highBits +（long）（uint）time.dwLowDateTime）; 
 
返回DateTime.FromFileTimeUtc（highBits |（long）（uint）time.dwLowDateTime）; 
 
 return DateTime.FromFileTimeUtc（highBits +（（long）low& 0xFFFFFFFF））
 
返回DateTime.FromFileTimeUtc（highBits |（（long）low& 0xFFFFFFFF）） 
  

您可以通过添加而不是按位来摆脱，或者如果您确定值为正（并没有任何共同之处）。但是按位或更好地表达意图。

Most of the files I read get the right time when using the following method to convert:

// works great most of the time
private static DateTime convertToDateTime(System.Runtime.InteropServices.ComTypes.FILETIME time)
{
    long highBits = time.dwHighDateTime;
    highBits = highBits << 32;
    return DateTime.FromFileTimeUtc(highBits + time.dwLowDateTime);
}

Here I have an example in visual studio to show how this method sometimes does not work for example I will show the actual file in my computer and the debug. So the file that happens to be in my debug is:

"A:\Users\Tono\Documents\Visual Studio 2010\Projects\WpfApplication4\WpfApplication4\obj\x86\Debug\App.g.cs"

And here is the FILETIME that I am trying to convert to DateTime "I need the LastWriteTime by the way"

Here you can see that dwHighDateTime = 30136437 and also that dwLowDateTime = -2138979250 from that file.

And when I run my method plus other techniques I get the following dates:

So so far everything seems to be working great. But why is that that when I browse and look for that specific file in windows I get a different date !? Here is the date that I get when seeing the file's properties:

Why does the dates don't match? What am I doing wrong?

解决方案

You need to combine the LS and MS values bitwise, not arithmetically.

Try:

        ulong high = 30136437;
        unchecked
        {
            int low = -2138979250;
            uint uLow = (uint)low;
            high = high << 32;
            Date dt = DateTime.FromFileTime((long) (high | (ulong)uLow));
        }

Or any of the following should work too:

long highBits = time.dwHighDateTime;     
highBits = highBits << 32;     

return DateTime.FromFileTimeUtc(highBits + (long) (uint) time.dwLowDateTime); 

return DateTime.FromFileTimeUtc(highBits | (long) (uint) time.dwLowDateTime); 

return DateTime.FromFileTimeUtc(highBits + ((long)low & 0xFFFFFFFF))

return DateTime.FromFileTimeUtc(highBits | ((long)low & 0xFFFFFFFF))

You can get away with adding rather than a bitwise-or if you are sure the values are positive (and have no bits in common). But bitwise-or expresses the intent better.

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