Defined in header <functional> | ||
|---|---|---|
template< class Arg, class Result >
std::pointer_to_unary_function<Arg,Result>
ptr_fun( Result (*f)(Arg) );
| (1) | (deprecated in C++11) (removed in C++17) |
template< class Arg1, class Arg2, class Result >
std::pointer_to_binary_function<Arg1,Arg2,Result>
ptr_fun( Result (*f)(Arg1, Arg2) );
| (2) | (deprecated in C++11) (removed in C++17) |
Creates a function wrapper object (either std::pointer_to_unary_function or std::pointer_to_binary_function), deducing the target type from the template arguments.
std::pointer_to_unary_function<Arg,Result>(f).std::pointer_to_binary_function<Arg1,Arg2,Result>(f).This function and the related types are deprecated as of C++11 in favor of the more general std::function and std::ref, both of which create callable adaptor-compatible function objects from plain functions.
| f | - | pointer to a function to create a wrapper for |
A function object wrapping f.
May throw implementation-defined exceptions.
#include <algorithm>
#include <functional>
#include <iostream>
#include <string_view>
constexpr bool is_vowel(char c)
{
return std::string_view{"aeoiuAEIOU"}.find(c) != std::string_view::npos;
}
int main()
{
std::string_view s = "Hello, world!";
std::ranges::copy_if(s, std::ostreambuf_iterator<char>(std::cout),
std::not1(std::ptr_fun(is_vowel)));
#if 0
// C++11 alternatives:
std::not1(std::cref(is_vowel)));
std::not1(std::function<bool(char)>(is_vowel)));
[](char c) { return !is_vowel(c); });
// C++17 alternatives:
std::not_fn(is_vowel));
#endif
}Output:
Hll, wrld!
|
(C++11) | wraps callable object of any copy constructible type with specified function call signature (class template) |
|
(C++23) | wraps callable object of any type with specified function call signature (class template) |
|
(C++17)(C++23) | invokes any Callable object with given arguments and possibility to specify return type (since C++23) (function template) |
|
(C++17) | creates a function object that returns the complement of the result of the function object it holds (function template) |
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