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TypeBuilder.DefinePInvokeMethod Method (String, String, String, MethodAttributes, CallingConventions, Type, Type[], CallingConvention, CharSet)

Defines a PInvoke method given its name, the name of the DLL in which the method is defined, the name of the entry point, the attributes of the method, the calling convention of the method, the return type of the method, the types of the parameters of the method, and the PInvoke flags.

Namespace:  System.Reflection.Emit
Assembly:  mscorlib (in mscorlib.dll)

public MethodBuilder DefinePInvokeMethod(
	string name,
	string dllName,
	string entryName,
	MethodAttributes attributes,
	CallingConventions callingConvention,
	Type returnType,
	Type[] parameterTypes,
	CallingConvention nativeCallConv,
	CharSet nativeCharSet


Type: System.String
The name of the PInvoke method. name cannot contain embedded nulls.
Type: System.String
The name of the DLL in which the PInvoke method is defined.
Type: System.String
The name of the entry point in the DLL.
Type: System.Reflection.MethodAttributes
The attributes of the method.
Type: System.Reflection.CallingConventions
The method's calling convention.
Type: System.Type
The method's return type.
Type: System.Type[]
The types of the method's parameters.
Type: System.Runtime.InteropServices.CallingConvention
The native calling convention.
Type: System.Runtime.InteropServices.CharSet
The method's native character set.

Return Value

Type: System.Reflection.Emit.MethodBuilder
The defined PInvoke method.


The method is not static.


The parent type is an interface.


The method is abstract.


The method was previously defined.


The length of name, dllName, or entryName is zero.


name, dllName, or entryName is null.


The containing type has been previously created using CreateType.

Some DLL import attributes (see the description of DllImportAttribute) cannot be specified as arguments to this method. For example, the DLL import attribute MethodImplAttributes.PreserveSig must be added after the PInvoke method is created, if the method returns a value. The example shows how to do this.

The following code example demonstrates how to use the DefinePInvokeMethod method to create a PInvoke method, and how to add the MethodImplAttributes.PreserveSig flag to the method implementation flags after you create the MethodBuilder, by using the MethodBuilder.GetMethodImplementationFlags and MethodBuilder.SetImplementationFlags methods.

Important noteImportant

To get a non-zero return value, you must add the MethodImplAttributes.PreserveSig flag.

The example creates a dynamic assembly with one dynamic module and a single type, MyType, that contains the PInvoke method. The PInvoke method represents the Win32 GetTickCount function.

When the example is run, it executes the PInvoke method. It also saves the dynamic assembly as PInvokeTest.dll. You can use the Ildasm.exe (MSIL Disassembler) to examine the MyType class and the static (Shared in Visual Basic) PInvoke method it contains. You can compile a Visual Basic or C# program that uses the static MyType.GetTickCount method by including a reference to the DLL when you run csc.exe or vbc.exe; for example, /r:PInvokeTest.dll.

using System;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

public class Example
    public static void Main()
        // Create the AssemblyBuilder.
        AssemblyName asmName = new AssemblyName("PInvokeTest");           
        AssemblyBuilder dynamicAsm = AppDomain.CurrentDomain.DefineDynamicAssembly(

        // Create the module.
        ModuleBuilder dynamicMod = 
            dynamicAsm.DefineDynamicModule(asmName.Name, asmName.Name + ".dll");

        // Create the TypeBuilder for the class that will contain the 
        // signature for the PInvoke call.
        TypeBuilder tb = dynamicMod.DefineType(
            TypeAttributes.Public | TypeAttributes.UnicodeClass

        MethodBuilder mb = tb.DefinePInvokeMethod(
            MethodAttributes.Public | MethodAttributes.Static | MethodAttributes.PinvokeImpl,

        // Add PreserveSig to the method implementation flags. NOTE: If this line
        // is commented out, the return value will be zero when the method is
        // invoked.
            mb.GetMethodImplementationFlags() | MethodImplAttributes.PreserveSig);

        // The PInvoke method does not have a method body. 

        // Create the class and test the method.
        Type t = tb.CreateType();

        MethodInfo mi = t.GetMethod("GetTickCount");
        Console.WriteLine("Testing PInvoke method...");
        Console.WriteLine("GetTickCount returned: {0}", mi.Invoke(null, null));

        // Produce the .dll file.
        Console.WriteLine("Saving: " + asmName.Name + ".dll");
        dynamicAsm.Save(asmName.Name + ".dll");

/* This example produces output similar to the following:

Testing PInvoke method...
GetTickCount returned: 1312576235
Saving: PInvokeTest.dll

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.