# std::indirectly_comparable

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< cpp‎ | iterator

Defined in header `<iterator>` |  |
template< class I1, class I2, class Comp, class Proj1 = std::identity, class Proj2 = std::identity > concept indirectly_comparable = std::indirect_binary_predicate <Comp, std:: projected <I1, Proj1>, std:: projected <I2, Proj2>>; |  | (since C++20)

The concept `indirectly_comparable` specifies the fundamental algorithm requirement for comparing values across two independent ranges.

### Semantic requirements

`indirectly_comparable` is modeled only if all concepts it subsumes are modeled.

### See also

indirect_binary_predicate (C++20) | specifies that a callable type, when invoked with the result of dereferencing two `indirectly_readable` types, satisfies `predicate` (concept)

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