unary_function<Arg, Result>


Category: functors	Component type: type

Description

Unary_function is an empty base class: it contains no member functions or member variables, but only type information. The only reason it exists is to make it more convenient to define types that are models of the concept Adaptable Unary Function. Specifically, any model of Adaptable Unary Function must define nested typedefs. Those typedefs are provided by the base class unary_function.

Example

struct sine : public unary_function<double, double> {
    double operator()(double x) { return sin(x); }
};

Definition

Defined in the standard header functional, and in the nonstandard backward-compatibility header function.h.

Template parameters

Parameter	Description	Default
`Arg`	The function object's argument type
`Result`	The function object's result type

Model of

Assignable, Default Constructible

Type requirements

Public base classes

None.

Members

Member	Where defined	Description
`argument_type`	`unary_function`	See below.
`result_type`	`unary_function`	See below.

New members

These members are not defined in the Assignable and Default Constructible requirements, but are specific to unary_function.

Member	Description
`argument_type`	The function object's argument type. This is a `typedef` for the template parameter `Arg`.
`result_type`	The function object's result type. This is a `typedef` for the template parameter `Result`.