pointer_to_unary_function Class

2018-01-02

The latest version of this topic can be found at pointer_to_unary_function Class.

Converts a unary function pointer into an adaptable unary function.

Syntax

template <class Arg, class Result>
class pointer_to_unary_function
 : public unary_function<Arg, Result>  
{
    public:
 explicit pointer_to_unary_function(
    Result (* _pfunc)(Arg));

    Result operator()(
    Arg left) const;

 };

Parameters

_pfunc
The binary function to be converted.

left
The object that the *_pfunc is called on.

Return Value

The template class stores a copy of _pfunc. It defines its member function operator() as returning (* _pfunc)(_ Left).

Remarks

A unary function pointer is a function object and may be passed to any Standard Template Library algorithm that is expecting a unary function as a parameter, but it is not adaptable. To use it with an adaptor, such as binding a value to it or using it with a negator, it must be supplied with the nested types argument_type and result_type that make such an adaptation possible. The conversion by pointer_to_unary_function allows the function adaptors to work with binary function pointers.

Example

The constructor of pointer_to_unary_function is rarely used directly. See the helper function ptr_fun for an example of how to declare and use the pointer_to_unary_function adaptor predicate.

Requirements

Header: <functional>

Namespace: std

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