StructLayoutAttribute Class

Definition

允许你控制内存中类或结构的数据字段的物理布局。Lets you control the physical layout of the data fields of a class or structure in memory.

public ref class StructLayoutAttribute sealed : Attribute
[System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Struct, Inherited=false)]
public sealed class StructLayoutAttribute : Attribute
[System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Struct, Inherited=false)]
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class StructLayoutAttribute : Attribute
type StructLayoutAttribute = class
    inherit Attribute
Public NotInheritable Class StructLayoutAttribute
Inherits Attribute
Inheritance
StructLayoutAttribute
Attributes

Examples

下面的示例演示 GetSystemTime 函数的托管声明,并定义具有 LayoutKind.Explicit 布局 MySystemTime 类。The following example demonstrates a managed declaration of the GetSystemTime function and defines MySystemTime class with LayoutKind.Explicit layout. GetSystemTime 获取系统时间,并将其打印到控制台。GetSystemTime gets the system time and prints to the console.

using namespace System;
using namespace System::Runtime::InteropServices;


[StructLayout(LayoutKind::Explicit,Size=16,CharSet=CharSet::Ansi)]
value class MySystemTime
{
public:

   [FieldOffset(0)]
   short wYear;

   [FieldOffset(2)]
   short wMonth;

   [FieldOffset(4)]
   short wDayOfWeek;

   [FieldOffset(6)]
   short wDay;

   [FieldOffset(8)]
   short wHour;

   [FieldOffset(10)]
   short wMinute;

   [FieldOffset(12)]
   short wSecond;

   [FieldOffset(14)]
   short wMilliseconds;
};

ref class NativeMethods
{
public:

   [DllImport("kernel32.dll")]
   static void GetSystemTime( MySystemTime * st );
};

int main()
{
   try
   {
      MySystemTime sysTime;
      NativeMethods::GetSystemTime(  &sysTime );
      Console::WriteLine( "The System time is {0}/{1}/{2} {3}:{4}:{5}", sysTime.wDay, sysTime.wMonth, sysTime.wYear, sysTime.wHour, sysTime.wMinute, sysTime.wSecond );
   }
   catch ( TypeLoadException^ e ) 
   {
      Console::WriteLine( "TypeLoadException : {0}", e->Message );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception : {0}", e->Message );
   }

}

using System;
using System.Runtime.InteropServices;

namespace InteropSample
{

   [StructLayout(LayoutKind.Explicit, Size=16, CharSet=CharSet.Ansi)]
   public class MySystemTime
   {
      [FieldOffset(0)]public ushort wYear;
      [FieldOffset(2)]public ushort wMonth;
      [FieldOffset(4)]public ushort wDayOfWeek;
      [FieldOffset(6)]public ushort wDay;
      [FieldOffset(8)]public ushort wHour;
      [FieldOffset(10)]public ushort wMinute;
      [FieldOffset(12)]public ushort wSecond;
      [FieldOffset(14)]public ushort wMilliseconds;
   }

   internal static class NativeMethods
   {
      [DllImport("kernel32.dll")]
      internal static extern void GetSystemTime([MarshalAs(UnmanagedType.LPStruct)]MySystemTime st);
   };

   class TestApplication
   {
      public static void Main()
      {
         try
         {
            MySystemTime sysTime = new MySystemTime();
            NativeMethods.GetSystemTime(sysTime);
            Console.WriteLine("The System time is {0}/{1}/{2} {3}:{4}:{5}", sysTime.wDay,
               sysTime.wMonth, sysTime.wYear, sysTime.wHour, sysTime.wMinute, sysTime.wSecond);
         }
         catch(TypeLoadException e)
         {
            Console.WriteLine("TypeLoadException : " + e.Message);
         }
         catch(Exception e)
         {
            Console.WriteLine("Exception : " + e.Message);
         }
      }
   }
}
Imports System.Runtime.InteropServices

Namespace InteropSample

   <StructLayout(LayoutKind.Explicit, Size:=16, CharSet:=CharSet.Ansi)> _
   Public Class MySystemTime
      <FieldOffset(0)> Public wYear As Short
      <FieldOffset(2)> Public wMonth As Short
      <FieldOffset(4)> Public wDayOfWeek As Short
      <FieldOffset(6)> Public wDay As Short
      <FieldOffset(8)> Public wHour As Short
      <FieldOffset(10)> Public wMinute As Short
      <FieldOffset(12)> Public wSecond As Short
      <FieldOffset(14)> Public wMilliseconds As Short
   End Class


   Friend Class NativeMethods

      <DllImport("kernel32.dll")> _
      Friend Shared Sub GetSystemTime(<MarshalAs(UnmanagedType.LPStruct)> ByVal st As MySystemTime)
      End Sub
   End Class

   Class TestApplication

      Public Shared Sub Main()
         Try
            Dim sysTime As New MySystemTime()
            NativeMethods.GetSystemTime(sysTime)
            Console.WriteLine("The System time is {0}/{1}/{2} {3}:{4}:{5}", sysTime.wDay, sysTime.wMonth, sysTime.wYear, sysTime.wHour, sysTime.wMinute, sysTime.wSecond)
         Catch e As TypeLoadException
            Console.WriteLine(("TypeLoadException : " + e.Message.ToString()))
         Catch e As Exception
            Console.WriteLine(("Exception : " + e.Message.ToString()))
         End Try
      End Sub
   End Class
End Namespace 'InteropSample 

Remarks

可以将此特性应用于类或结构。You can apply this attribute to classes or structures.

公共语言运行时控制托管内存中类或结构的数据字段的物理布局。The common language runtime controls the physical layout of the data fields of a class or structure in managed memory. 但是,如果要将类型传递给非托管代码,则可以使用 StructLayoutAttribute 特性来控制类型的非托管布局。However, if you want to pass the type to unmanaged code, you can use the StructLayoutAttribute attribute to control the unmanaged layout of the type. 使用带有 LayoutKind.Sequential 的属性,强制按成员的显示顺序对其进行排列。Use the attribute with LayoutKind.Sequential to force the members to be laid out sequentially in the order they appear. 对于直接类型的类型,LayoutKind.Sequential 在托管内存和非托管内存中控制布局。For blittable types, LayoutKind.Sequential controls both the layout in managed memory and the layout in unmanaged memory. 对于不可直接复制的类型,它会在将类或结构封送到非托管代码时控制布局,但不会控制托管内存中的布局。For non-blittable types, it controls the layout when the class or structure is marshaled to unmanaged code, but does not control the layout in managed memory. 使用带有 LayoutKind.Explicit 的属性可控制每个数据成员的精确位置。Use the attribute with LayoutKind.Explicit to control the precise position of each data member. 这会影响托管和非托管布局,同时用于本机和非直接复制类型。This affects both managed and unmanaged layout, for both blittable and non-blittable types. 使用 LayoutKind.Explicit 要求你使用 FieldOffsetAttribute 属性指示类型中每个字段的位置。Using LayoutKind.Explicit requires that you use the FieldOffsetAttribute attribute to indicate the position of each field within the type.

C#默认情况下, C++ Visual Basic 和编译器会将 Sequential 布局值应用到结构。C#, Visual Basic, and C++ compilers apply the Sequential layout value to structures by default. 对于类,必须显式应用 LayoutKind.Sequential 值。For classes, you must apply the LayoutKind.Sequential value explicitly. Tlbimp.exe (类型库导入程序)也应用 StructLayoutAttribute 特性;它在导入类型库时始终应用 LayoutKind.Sequential 值。The Tlbimp.exe (Type Library Importer) also applies the StructLayoutAttribute attribute; it always applies the LayoutKind.Sequential value when it imports a type library.

Constructors

StructLayoutAttribute(Int16)

使用指定的 LayoutKind 枚举成员初始化 StructLayoutAttribute 类的新实例。Initializes a new instance of the StructLayoutAttribute class with the specified LayoutKind enumeration member.

StructLayoutAttribute(LayoutKind)

使用指定的 LayoutKind 枚举成员初始化 StructLayoutAttribute 类的新实例。Initializes a new instance of the StructLayoutAttribute class with the specified LayoutKind enumeration member.

Fields

CharSet

指示在默认情况下是否应将类中的字符串数据字段作为 LPWSTRLPSTR 进行封送处理。Indicates whether string data fields within the class should be marshaled as LPWSTR or LPSTR by default.

Pack

控制类或结构的数据字段在内存中的对齐方式。Controls the alignment of data fields of a class or structure in memory.

Size

指示类或结构的绝对大小。Indicates the absolute size of the class or structure.

Properties

TypeId

在派生类中实现时,获取此 Attribute 的唯一标识符。When implemented in a derived class, gets a unique identifier for this Attribute.

(Inherited from Attribute)
Value

获取 LayoutKind 值,该值指定如何排列类或结构。Gets the LayoutKind value that specifies how the class or structure is arranged.

Methods

Equals(Object)

返回一个值,该值指示此实例是否与指定的对象相等。Returns a value that indicates whether this instance is equal to a specified object.

(Inherited from Attribute)
GetHashCode()

返回此实例的哈希代码。Returns the hash code for this instance.

(Inherited from Attribute)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
IsDefaultAttribute()

在派生类中重写时,指示此实例的值是否是派生类的默认值。When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.

(Inherited from Attribute)
Match(Object)

当在派生类中重写时,返回一个指示此实例是否等于指定对象的值。When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(Inherited from Attribute)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

Explicit Interface Implementations

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

将一组名称映射为对应的一组调度标识符。Maps a set of names to a corresponding set of dispatch identifiers.

(Inherited from Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

检索对象的类型信息,然后可以使用该信息获取接口的类型信息。Retrieves the type information for an object, which can be used to get the type information for an interface.

(Inherited from Attribute)
_Attribute.GetTypeInfoCount(UInt32)

检索对象提供的类型信息接口的数量(0 或 1)。Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Inherited from Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

提供对某一对象公开的属性和方法的访问。Provides access to properties and methods exposed by an object.

(Inherited from Attribute)

Applies to

See also