InAttribute Class
Indicates that data should be marshaled from the caller to the callee, but not back to the caller.
Assembly: mscorlib (in mscorlib.dll)
The InAttribute type exposes the following members.
| Name | Description | |
|---|---|---|
![]() ![]() | Equals | Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.) |
![]() ![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() ![]() | GetHashCode | Returns the hash code for this instance. (Inherited from Attribute.) |
![]() ![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | IsDefaultAttribute | 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 | When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.) |
![]() ![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() ![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
| Name | Description | |
|---|---|---|
![]() ![]() | _Attribute::GetIDsOfNames | Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.) |
![]() ![]() | _Attribute::GetTypeInfo | Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.) |
![]() ![]() | _Attribute::GetTypeInfoCount | Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.) |
![]() ![]() | _Attribute::Invoke | Provides access to properties and methods exposed by an object. (Inherited from Attribute.) |
You can apply this attribute to parameters.
The InAttribute is optional. The attribute is supported for COM interop and platform invoke only. In the absence of explicit settings, the interop marshaler assumes rules based on the parameter type, whether the parameter is passed by reference or by value, and whether the type is blittable or non-blittable. For example, the StringBuilder class is always assumed to be In/Out and an array of strings passed by value is assumed to be In.
You cannot apply the InAttribute to a parameter modified with the C#-styled out keyword. To avoid confusing the In keyword in Visual Basic with the InAttribute, minus Attribute, use the <[In]> form with brackets around the attribute.
Combining the InAttribute and OutAttribute is particularly useful when applied to arrays and formatted, non-blittable types. Callers see the changes a callee makes to these types only when you apply both attributes. Since these types require copying during marshaling, you can use InAttribute and OutAttribute to reduce unnecessary copies.
For more information on the effect of InAttribute on marshaling behavior, see Directional Attributes.
The following example shows how to apply the InAttribute and OutAttribute to a platform invoke prototype that passes an array as a parameter. The combination of directional attributes allows the caller to see the changes made by the callee.
using namespace System; using namespace System::Runtime::InteropServices; // Declare a class member for each structure element. [StructLayout(LayoutKind::Sequential,CharSet=CharSet::Unicode)] public ref class OpenFileName { public: int structSize; String^ filter; String^ file; // ... }; public ref class LibWrap { public: // Declare a managed prototype for the unmanaged function. [DllImport("Comdlg32.dll",CharSet=CharSet::Unicode)] static bool GetOpenFileName( [In,Out]OpenFileName^ ofn ); }; void main() {}
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.
