std::ptr_fun
From cppreference.com
< cpp | utility | functional
Defined in header <functional>
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template< class Arg, class Result > std::pointer_to_unary_function<Arg,Result> |
(1) | (deprecated in C++11) (removed in C++17) |
template< class Arg1, class Arg2, class Result > std::pointer_to_binary_function<Arg1,Arg2,Result> |
(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.
1) Effectively calls std::pointer_to_unary_function<Arg,Result>(f).
2) Effectively calls 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.
Contents |
[edit] Parameters
f | - | pointer to a function to create a wrapper for |
[edit] Return value
A function object wrapping f.
[edit] Exceptions
May throw implementation-defined exceptions.
[edit] Example
Run this code
#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!
[edit] See also
(C++11) |
copyable wrapper of any copy constructible callable object (class template) |
(C++23) |
move-only wrapper of any callable object that supports qualifiers in a given 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) |