TypeBuilder.DefinePInvokeMethod Method (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 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,
	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.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.

Exception Condition

The method is not static.


The parent type is an interface.


The method is abstract.


The method was previously defined.


The length of name or dllName is zero.


name or dllName 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 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.


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 (IL 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
Available since 1.1
Available since 2.0
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