pointer_to_unary_function Class
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