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Directory.GetLastWriteTimeUtc 方法

返回上次写入指定文件或目录的日期和时间,其格式为协调通用时间 (UTC)。

命名空间:  System.IO
程序集:  mscorlib(在 mscorlib.dll 中)
public static DateTime GetLastWriteTimeUtc(
	string path
)

参数

path
类型:System.String
要获取其修改日期和时间信息的文件或目录。

返回值

类型:System.DateTime
一个结构,它被设置为上次写入指定文件或目录的日期和时间。 该值用 UTC 时间表示。
异常条件
UnauthorizedAccessException

调用方没有所要求的权限。

ArgumentException

path 是一个零长度字符串,仅包含空白或者包含一个或多个由 InvalidPathChars 定义的无效字符。

ArgumentNullException

pathnull

PathTooLongException

指定的路径、文件名或者两者都超出了系统定义的最大长度。 例如,在基于 Windows 的平台上,路径必须小于 248 个字符,文件名必须小于 260 个字符。

说明说明

This method may return an inaccurate value, because it uses native functions whose values may not be continuously updated by the operating system.

If the directory described in the path parameter does not exist, this method returns 12:00 midnight, January 1, 1601 A.D.(C.E.)Coordinated Universal Time (UTC).

For a list of common I/O tasks, see 通用 I/O 任务.

The following example illustrates the differences in output when using Coordinated Universal Time (UTC) output.


// This sample shows the differences between dates from methods that use
//coordinated universal time (UTC) format and those that do not.
using System;
using System.IO;

namespace IOSamples
{
  public class DirectoryUTCTime
  {
    public static void Main()
    {
	// Set the directory.
      string n = @"C:\test\newdir";
		//Create two variables to use to set the time.
	  DateTime dtime1 = new DateTime(2002, 1, 3);
	  DateTime dtime2 = new DateTime(1999, 1, 1);

	//Create the directory.
	  try
	  {
		  Directory.CreateDirectory(n);
	  }
	  catch (IOException e)
	  {
		  Console.WriteLine(e);
	  }

	//Set the creation and last access times to a variable DateTime value.
	  Directory.SetCreationTime(n, dtime1);
	  Directory.SetLastAccessTimeUtc(n, dtime1);

		// Print to console the results.
	  Console.WriteLine("Creation Date: {0}", Directory.GetCreationTime(n));
	  Console.WriteLine("UTC creation Date: {0}", Directory.GetCreationTimeUtc(n));
	  Console.WriteLine("Last write time: {0}", Directory.GetLastWriteTime(n));
	  Console.WriteLine("UTC last write time: {0}", Directory.GetLastWriteTimeUtc(n));
	  Console.WriteLine("Last access time: {0}", Directory.GetLastAccessTime(n));
	  Console.WriteLine("UTC last access time: {0}", Directory.GetLastAccessTimeUtc(n));

		//Set the last write time to a different value.
      Directory.SetLastWriteTimeUtc(n, dtime2);
	  Console.WriteLine("Changed last write time: {0}", Directory.GetLastWriteTimeUtc(n));
    }
  }
}
// Obviously, since this sample deals with dates and times, the output will vary
// depending on when you run the executable. Here is one example of the output:
//Creation Date: 1/3/2002 12:00:00 AM
//UTC creation Date: 1/3/2002 8:00:00 AM
//Last write time: 12/31/1998 4:00:00 PM
//UTC last write time: 1/1/1999 12:00:00 AM
//Last access time: 1/2/2002 4:00:00 PM
//UTC last access time: 1/3/2002 12:00:00 AM
//Changed last write time: 1/1/1999 12:00:00 AM



.NET Framework

受以下版本支持:4.5、4、3.5、3.0、2.0、1.1

.NET Framework Client Profile

受以下版本支持:4、3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008(不支持服务器核心角色), Windows Server 2008 R2(支持带 SP1 或更高版本的服务器核心角色;不支持 Itanium)

并不是.NET Framework 对每个平台的所有版本都提供支持。有关支持的版本的列表,请参见.NET Framework 系统要求.
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