std::not_equal_to<void>

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Utilities library

Language support

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Library feature-test macros(C++20)

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initializer_list

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(C++20)

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common_comparison_category

(C++20)

compare_three_way_result

(C++20)

(C++20)

(C++20)

(C++20)

(C++20)

compare_strong_order_fallback

(C++20)

compare_weak_order_fallback

(C++20)

compare_partial_order_fallback

(C++20)

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(C++20)(C++20)(C++20)

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Function objects

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function (C++11)
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Partial function application
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equal_to
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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*)

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Defined in header`<functional>`
template<> class not_equal_to<void>;		(since C++14)

std::not_equal_to<void> is a specialization ofstd::not_equal_to with parameter and return type deduced.

[edit]Nested types

Nested type	Definition
`is_transparent`	unspecified

[edit]Member functions

operator()

tests if the two arguments do not compare equal
(public member function)

std::not_equal_to<void>::operator()

template<class T,class U> constexprauto operator()( T&& lhs, U&& rhs)const -> decltype(std::forward<T>(lhs)!=std::forward<U>(rhs));

Returns the result of non-equality comparison betweenlhs andrhs.

Parameters

lhs, rhs

values to compare

Return value

std::forward<T>(lhs)!=std::forward<U>(rhs).

[edit]Example

Run this code

#include <functional> int main(){constexprint p=0, q=8;std::not_equal_to<> not_equal{};    static_assert(!not_equal(p, p));    static_assert(not_equal(p, q));}