StructLayoutAttribute Class

Definition

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

Object

Attribute

StructLayoutAttribute

Attributes

AttributeUsageAttribute ComVisibleAttribute

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

Fields

Properties

Methods

Explicit Interface Implementations

Applies to

See also

• Tlbimp.exe（类型库导入程序）Tlbimp.exe (Type Library Importer)