in attribute

The [in] attribute indicates that a parameter is to be passed from the calling procedure to the called procedure.

[ [function-attribute-list] ] type-specifier [pointer-declarator] function-name(
    [ in [ , parameter-attribute-list ] ] type-specifier [declarator]
    , ...);



Specifies zero or more attributes that apply to the function. Valid function attributes are [callback], [local], the pointer attribute [ref], [unique], or [ptr], and the usage attributes [string], [ignore], and [context_handle].


Specifies a base_type, struct, union, or enum type or type identifier. An optional storage specification can precede type-specifier.


Specifies zero or more pointer declarators. A pointer declarator is the same as the pointer declarator used in C; it is constructed from the * designator, modifiers such as far, and the qualifier const.


Specifies the name of the remote procedure.


Specifies zero or more attributes appropriate for the specified parameter type. Parameter attributes with the [in] attribute can also take the directional attribute [out]; the field attributes [first_is], [last_is], [length_is], [max_is], [size_is] and [switch_type]; the pointer attribute [ref], [unique], or [ptr]; and the usage attributes [context_handle] and [string]. The usage attribute [ignore] cannot be used as a parameter attribute. Separate multiple attributes with commas.


Specifies standard C declarators, such as identifiers, pointer declarators, and array declarators. For more information, see Array and Sized-Pointer Attributes, arrays, and Arrays and Pointers. The parameter declarator in the function declarator, such as the parameter name, is optional.


The [in] attribute has a converse attribute, [out], which indicates that a parameter is to be returned from the called procedure to the calling procedure. The [in] and [out] attributes are known as directional parameter attributes because they specify the direction in which parameters are passed. A parameter can be defined as [in], [out], or [in, out].

The [in] attribute identifies parameters that are marshaled by the client stub for transmission to the server.

The [in] attribute is applied to a parameter by default when no directional parameter attribute is specified.


HRESULT MyFunction([in] short count);

See also

Interface Definition (IDL) File