std::cmp_equal, cmp_not_equal, cmp_less, cmp_greater, cmp_less_equal, cmp_greater_equal

 

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Defined in header <utility>
template< class T, class U > constexpr bool cmp_equal( T t, U u ) noexcept;	(1)	(since C++20)
template< class T, class U > constexpr bool cmp_not_equal( T t, U u ) noexcept;	(2)	(since C++20)
template< class T, class U > constexpr bool cmp_less( T t, U u ) noexcept;	(3)	(since C++20)
template< class T, class U > constexpr bool cmp_greater( T t, U u ) noexcept;	(4)	(since C++20)
template< class T, class U > constexpr bool cmp_less_equal( T t, U u ) noexcept;	(5)	(since C++20)
template< class T, class U > constexpr bool cmp_greater_equal( T t, U u ) noexcept;	(6)	(since C++20)

Compare the values of two integers t and u. Unlike builtin comparison operators, negative signed integers always compare less than (and not equal to) unsigned integers: the comparison is safe against lossy integer conversion.

-1 > 0u; // true
std::cmp_greater(-1, 0u); // false

It is a compile-time error if either T or U is not a standard integer type or extended integer type.

Parameters

t	-	left-hand argument
u	-	right-hand argument

Return value

1) true if t is equal to u.

2) true if t is not equal to u.

3) true if t is less than u.

4) true if t is greater than u.

5) true if t is less or equal to u.

6) true if t is greater or equal to u.

Possible implementation

template< class T, class U > constexpr bool cmp_equal( T t, U u ) noexcept { using UT = std::make_unsigned_t<T>; using UU = std::make_unsigned_t<U>; if constexpr (std::is_signed_v<T> == std::is_signed_v<U>) return t == u; else if constexpr (std::is_signed_v<T>) return t < 0 ? false : UT(t) == u; else return u < 0 ? false : t == UU(u); }   template< class T, class U > constexpr bool cmp_not_equal( T t, U u ) noexcept { return !cmp_equal(t, u); }   template< class T, class U > constexpr bool cmp_less( T t, U u ) noexcept { using UT = std::make_unsigned_t<T>; using UU = std::make_unsigned_t<U>; if constexpr (std::is_signed_v<T> == std::is_signed_v<U>) return t < u; else if constexpr (std::is_signed_v<T>) return t < 0 ? true : UT(t) < u; else return u < 0 ? false : t < UU(u); }   template< class T, class U > constexpr bool cmp_greater( T t, U u ) noexcept { return cmp_less(u, t); }   template< class T, class U > constexpr bool cmp_less_equal( T t, U u ) noexcept { return !cmp_greater(t, u); }   template< class T, class U > constexpr bool cmp_greater_equal( T t, U u ) noexcept { return !cmp_less(t, u); }

Notes

These functions cannot be used to compare std::byte, char, char8_t, char16_t, char32_t, wchar_t and bool.