TypeBuilder.DefineUninitializedData(String, Int32, FieldAttributes) Method

Definition

Namespace:

System.Reflection.Emit

Assembly:

System.Reflection.Emit.dll

Source:

TypeBuilder.cs

Defines an uninitialized data field in the .sdata section of the portable executable (PE) file.

public:
 System::Reflection::Emit::FieldBuilder ^ DefineUninitializedData(System::String ^ name, int size, System::Reflection::FieldAttributes attributes);

public System.Reflection.Emit.FieldBuilder DefineUninitializedData (string name, int size, System.Reflection.FieldAttributes attributes);

member this.DefineUninitializedData : string * int * System.Reflection.FieldAttributes -> System.Reflection.Emit.FieldBuilder

Public Function DefineUninitializedData (name As String, size As Integer, attributes As FieldAttributes) As FieldBuilder

Parameters

name

String

The name used to refer to the data. name cannot contain embedded nulls.

size

Int32

The size of the data field.

attributes

FieldAttributes

The attributes for the field.

Returns

FieldBuilder

A field to reference the data.

Exceptions

ArgumentException

Length of name is zero.

-or-

size is less than or equal to zero, or greater than or equal to 0x003f0000.

ArgumentNullException

name is null.

InvalidOperationException

The type was previously created using CreateType().

Examples

The following code sample demonstrates the use of DefineUninitializedData to create an uninitialized data field in a dynamic type:

using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
using namespace System::Runtime::InteropServices;
using namespace System::Security::Permissions;

public ref class Example
{
public:
   [SecurityPermission(SecurityAction::Demand, Flags=SecurityPermissionFlag::UnmanagedCode)]
   static void Main()
   {
      Type^ myHelloWorldType = CreateCallee( Thread::GetDomain() );
      Object^ myHelloWorldInstance = Activator::CreateInstance( myHelloWorldType );
      FieldInfo^ myGreetingFieldInfo = myHelloWorldType->GetField( "MyGreeting" );
      Object^ oval = Activator::CreateInstance( myGreetingFieldInfo->FieldType );
      IntPtr myIntPtr = Marshal::AllocHGlobal( 4 );
      Random^ rand = gcnew Random;
      int iTempSeed = rand->Next();
      array<Byte>^bINITBYTE = GetRandBytes( iTempSeed, 4 );
      IntPtr intptrTemp = myIntPtr;
      for ( int j = 0; j < 4; j++ )
      {
         Marshal::WriteByte( myIntPtr, bINITBYTE[ j ] );
         myIntPtr = (IntPtr)((int)myIntPtr + 1);

      }
      myIntPtr = intptrTemp;
      Object^ oValNew = Marshal::PtrToStructure( myIntPtr, myGreetingFieldInfo->FieldType );
      Marshal::FreeHGlobal( myIntPtr );
      myIntPtr = Marshal::AllocHGlobal( 4 );
      Object^ myObj = myGreetingFieldInfo->GetValue( myHelloWorldInstance );
      Marshal::StructureToPtr( myObj, myIntPtr, true );
      intptrTemp = myIntPtr;
      Console::WriteLine( "The value of 'MyGreeting' field : " );
      for ( int j = 0; j < 4; j++ )
      {
         Marshal::WriteByte( myIntPtr, bINITBYTE[ j ] );
         Console::WriteLine( bINITBYTE[ j ] );
         myIntPtr = (IntPtr)((int)myIntPtr + 1);

      }
   }


private:
   static array<Byte>^ GetRandBytes( int iRandSeed, int iSize )
   {
      array<Byte>^barr = gcnew array<Byte>(iSize);
      Random^ randTemp = gcnew Random( iRandSeed );
      randTemp->NextBytes( barr );
      return barr;
   }


   // Create the callee transient dynamic assembly.
   static Type^ CreateCallee( AppDomain^ myDomain )
   {
      
      // Create a simple name for the callee assembly.
      AssemblyName^ myAssemblyName = gcnew AssemblyName;
      myAssemblyName->Name = "EmittedClass";
      
      // Create the callee dynamic assembly.
      AssemblyBuilder^ myAssembly = myDomain->DefineDynamicAssembly( myAssemblyName, AssemblyBuilderAccess::Run );
      
      // Create a dynamic module in the callee assembly.
      ModuleBuilder^ myModule = myAssembly->DefineDynamicModule( "EmittedModule" );
      
      // Define a public class named "MyHelloWorld"
      TypeBuilder^ myHelloWorldType = myModule->DefineType( "MyHelloWorld", TypeAttributes::Public );
      
      // Define a 'MyGreeting' field and initialize it.
      FieldBuilder^ myFieldBuilder = myHelloWorldType->DefineUninitializedData( "MyGreeting", 4, FieldAttributes::Public );
      
      // Create the 'MyHelloWorld' class.
      return (myHelloWorldType->CreateType());
   }

};

int main()
{
   Example::Main();
}

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;
using System.Security.Permissions;

public sealed class Example
{
   public static void Main()
   {
      Type myHelloWorldType = CreateCallee(Thread.GetDomain());
      object myHelloWorldInstance =
      Activator.CreateInstance(myHelloWorldType);
      FieldInfo myGreetingFieldInfo =
      myHelloWorldType.GetField("MyGreeting");
      object oval = Activator.CreateInstance(myGreetingFieldInfo.FieldType);
      IntPtr myIntPtr = Marshal.AllocHGlobal(4);
      Random rand = new Random();
      int iTempSeed = rand.Next();
      byte[] bINITBYTE = GetRandBytes( iTempSeed, 4);
      IntPtr intptrTemp = myIntPtr;
      for ( int j = 0; j < 4; j++ )
      {
         Marshal.WriteByte( myIntPtr, bINITBYTE[j]);
         myIntPtr = (IntPtr)((int)myIntPtr + 1);
      }
      myIntPtr = intptrTemp;
      Object oValNew = Marshal.PtrToStructure( myIntPtr, myGreetingFieldInfo.FieldType);
      Marshal.FreeHGlobal( myIntPtr );

      myIntPtr = Marshal.AllocHGlobal(4);
      object myObj = myGreetingFieldInfo.GetValue(myHelloWorldInstance);
      Marshal.StructureToPtr(myObj, myIntPtr, true);
      intptrTemp = myIntPtr;
      Console.WriteLine("The value of 'MyGreeting' field : ");
      for ( int j = 0; j < 4; j++ )
      {
         Marshal.WriteByte( myIntPtr, bINITBYTE[j]);
         Console.WriteLine(bINITBYTE[j]);
         myIntPtr = (IntPtr)((int)myIntPtr + 1);
      }
   }

   private static byte[] GetRandBytes( int iRandSeed, int iSize )
   {
      byte[] barr = new byte[iSize];
      Random randTemp = new Random( iRandSeed );
      randTemp.NextBytes( barr );
      return barr;
   }

   // Create the callee transient dynamic assembly.
   private static Type CreateCallee(AppDomain myDomain)
   {
      // Create a simple name for the callee assembly.
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "EmittedClass";

      // Create the callee dynamic assembly.
      AssemblyBuilder myAssembly =
         myDomain.DefineDynamicAssembly(myAssemblyName,AssemblyBuilderAccess.Run);

      // Create a dynamic module in the callee assembly.
      ModuleBuilder myModule =
         myAssembly.DefineDynamicModule("EmittedModule");

      // Define a public class named "MyHelloWorld"
      TypeBuilder myHelloWorldType =
         myModule.DefineType("MyHelloWorld", TypeAttributes.Public);

      // Define a 'MyGreeting' field and initialize it.
      FieldBuilder myFieldBuilder =
         myHelloWorldType.DefineUninitializedData("MyGreeting",4,FieldAttributes.Public);

      // Create the 'MyHelloWorld' class.
      return(myHelloWorldType.CreateType());
   }

   private Example() {}
}

Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Runtime.InteropServices


Module Example

   Sub Main()
      Dim myHelloWorldType As Type = CreateCallee(Thread.GetDomain())
      Dim myHelloWorldInstance As Object = Activator.CreateInstance(myHelloWorldType)
      Dim myGreetingFieldInfo As FieldInfo = myHelloWorldType.GetField("MyGreeting")
      Dim oval As Object = Activator.CreateInstance(myGreetingFieldInfo.FieldType)
      Dim myIntPtr As IntPtr = Marshal.AllocHGlobal(4)
      Dim rand As New Random()
      Dim iTempSeed As Integer = rand.Next()
      Dim bINITBYTE As Byte() = GetRandBytes(iTempSeed, 4)
      Dim intptrTemp As IntPtr = myIntPtr
      Dim j As Integer
      For j = 0 To 3
         Marshal.WriteByte(myIntPtr, bINITBYTE(j))
         myIntPtr = intptr.op_Explicit(myIntPtr.ToInt32 + 1)
      Next j
      myIntPtr = intptrTemp
      Dim oValNew As [Object] = Marshal.PtrToStructure(myIntPtr, myGreetingFieldInfo.FieldType)
      Marshal.FreeHGlobal(myIntPtr)

      myIntPtr = Marshal.AllocHGlobal(4)
      Dim myObj As Object = myGreetingFieldInfo.GetValue(myHelloWorldInstance)
      Marshal.StructureToPtr(myObj, myIntPtr, True)
      intptrTemp = myIntPtr
      Console.WriteLine("The value of 'MyGreeting' field : ")

      For j = 0 To 3
         Marshal.WriteByte(myIntPtr, bINITBYTE(j))
         Console.WriteLine(bINITBYTE(j))
         myIntPtr = intptr.op_Explicit(myIntPtr.ToInt32 + 1)
      Next j
   End Sub


   Private Function GetRandBytes(ByVal iRandSeed As Integer, ByVal iSize As Integer) As Byte()
      Dim barr(iSize) As Byte
      Dim randTemp As New Random(iRandSeed)
      randTemp.NextBytes(barr)
      Return barr
   End Function 'GetRandBytes


   ' Create the callee transient dynamic assembly.
   Private Function CreateCallee(ByVal myDomain As AppDomain) As Type
      ' Create a simple name for the callee assembly.
      Dim myAssemblyName As New AssemblyName()
      myAssemblyName.Name = "EmittedClass"

      ' Create the callee dynamic assembly.
      Dim myAssembly As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAssemblyName, AssemblyBuilderAccess.Run)


      ' Create a dynamic module in the callee assembly.
      Dim myModule As ModuleBuilder = myAssembly.DefineDynamicModule("EmittedModule")

      ' Define a public class named "MyHelloWorld"
      Dim myHelloWorldType As TypeBuilder = myModule.DefineType("MyHelloWorld", TypeAttributes.Public)

      ' Define a 'MyGreeting' field and initialize it.
      Dim myFieldBuilder As FieldBuilder = myHelloWorldType.DefineUninitializedData("MyGreeting", 4, FieldAttributes.Public)

      ' Create the 'MyHelloWorld' class.
      Return myHelloWorldType.CreateType()
   End Function 'CreateCallee

End Module

Remarks

The field that you create with this method will be static, even if you do not include FieldAttributes.Static in the attributes parameter.