std::ptr_fun

 

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Language support Type support (basic types, RTTI) Library feature-test macros(C++20) Program utilities Variadic functions initializer_list (C++11) is_constant_evaluated (C++20) is_within_lifetime (C++26) source_location (C++20) Coroutine support(C++20) Contract support(C++26) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Function objects Bit manipulation(C++20) bitset hash (C++11) Relational operators(deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23)

 

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Function wrappers function (C++11) move_only_function (C++23) copyable_function (C++26) function_ref (C++26) mem_fn (C++11) bad_function_call (C++11)	Partial function application bind_frontbind_back (C++20)(C++23) bind (C++11) is_bind_expression (C++11) is_placeholder (C++11) _1, _2, _3, ... (C++11)
Function invocation invokeinvoke_r (C++17)(C++23) Identity function object identity (C++20)	Reference wrappers reference_wrapper (C++11) refcref (C++11)(C++11) unwrap_referenceunwrap_ref_decay (C++20)(C++20)
Operator wrappers plus minus negate multiplies divides modulus bit_and bit_or bit_not (C++14)   bit_xor equal_to not_equal_to greater less greater_equal less_equal logical_and logical_or logical_not	Transparent operator wrappers plus<> (C++14) minus<> (C++14) negate<> (C++14) multiplies<> (C++14)   divides<> (C++14) modulus<> (C++14) bit_and<> (C++14) bit_or<> (C++14) bit_not<> (C++14) bit_xor<> (C++14) equal_to<> (C++14) not_equal_to<> (C++14) greater<> (C++14) less<> (C++14) greater_equal<> (C++14) less_equal<> (C++14) logical_and<> (C++14) logical_or<> (C++14) logical_not<> (C++14)
Negators not_fn (C++17) Searchers default_searcher (C++17) boyer_moore_searcher (C++17) boyer_moore_horspool_searcher (C++17)	Constrained comparators ranges::equal_to (C++20) ranges::not_equal_to (C++20) ranges::greater (C++20) ranges::less (C++20) ranges::greater_equal (C++20) ranges::less_equal (C++20) compare_three_way (C++20)
Old binders and adaptors
unary_function (until C++17*) binary_function (until C++17*) ptr_fun (until C++17*) pointer_to_unary_function (until C++17*) pointer_to_binary_function (until C++17*)   mem_fun (until C++17*) mem_fun_tmem_fun1_tconst_mem_fun_tconst_mem_fun1_t (until C++17*)(until C++17*)(until C++17*)(until C++17*) not1 (until C++20*) not2 (until C++20*)	binder1stbinder2nd (until C++17*)(until C++17*) bind1stbind2nd (until C++17*)(until C++17*) mem_fun_ref (until C++17*) mem_fun_ref_tmem_fun1_ref_tconst_mem_fun_ref_tconst_mem_fun1_ref_t (until C++17*)(until C++17*)(until C++17*)(until C++17*) unary_negate (until C++20*) binary_negate (until C++20*)

 

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.

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.

Parameters

f

-

pointer to a function to create a wrapper for

Return value

A function object wrapping f.

Exceptions

May throw implementation-defined exceptions.

Example

Run this code

#include <algorithm>#include <functional>#include <iostream>#include <string_view>   constexprbool is_vowel(char c){returnstd::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!

See also

function (C++11)	copyable wrapper of any copy constructible callable object (class template)
move_only_function (C++23)	move-only wrapper of any callable object that supports qualifiers in a given call signature (class template)
invokeinvoke_r (C++17)(C++23)	invokes any Callable object with given arguments and possibility to specify return type(since C++23) (function template)
not_fn (C++17)	creates a function object that returns the complement of the result of the function object it holds (function template)