std::is_eq, std::is_neq, std::is_lt, std::is_gt, std::is_lteq, std::is_gteq

From cppreference.com
< cpp‎ | utility
Defined in header <compare>
constexpr bool is_eq(std::weak_equality cmp) noexcept;
(1) (since C++20)
constexpr bool is_neq(std::weak_equality cmp) noexcept;
(2) (since C++20)
constexpr bool is_lt(std::partial_ordering cmp) noexcept;
(3) (since C++20)
constexpr bool is_lteq(std::partial_ordering cmp) noexcept;
(4) (since C++20)
constexpr bool is_gt(std::partial_ordering cmp) noexcept;
(5) (since C++20)
constexpr bool is_gteq(std::partial_ordering cmp) noexcept
(6) (since C++20)

These functions take a result of 3-way comparison and convert it to the result of one of the six relational operators

Specifically, these functions return

1) cmp == 0
2) cmp != 0
3) cmp < 0
4) cmp <= 0
5) cmp > 0
6) cmp >= 0

Parameters

cmp - result of 3-way comparison

Return value

bool result of the corresponding relational operation

Example

See also

the result type of 3-way comparison that supports all 6 operators, is not substitutable, and allows incomparable values
(class)
the result type of 3-way comparison that supports only equality/inequality and is not substitutable
(class)