# operator==,!=,<,<=,>,>=,<=>(std::sub_match)

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< cpp‎ | regex‎ | sub match

Defined in header `<regex>` |  |
Direct comparison |  |
template< class BidirIt > bool operator==( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (1) | (since C++11)
template< class BidirIt > bool operator!=( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (2) | (since C++11) (until C++20)
template< class BidirIt > bool operator<( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (3) | (since C++11) (until C++20)
template< class BidirIt > bool operator<=( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (4) | (since C++11) (until C++20)
template< class BidirIt > bool operator>( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (5) | (since C++11) (until C++20)
template< class BidirIt > bool operator>=( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (6) | (since C++11) (until C++20)
template< class BidirIt > /*comp-cat*/ operator<=>( const std::sub_match<BidirIt>& lhs, const std::sub_match<BidirIt>& rhs ); | (7) | (since C++20)
`std::sub_match` and `std::basic_string` |  |
template< class BidirIt, class Traits, class Alloc > bool operator==( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& rhs ); | (8) | (since C++11)
template< class BidirIt, class Traits, class Alloc > bool operator!=( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (9) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator<( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (10) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator<=( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (11) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator>( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (12) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator>=( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (13) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > /*comp-cat*/ operator<=>( const std::sub_match<BidirIt>& sm, const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st ); | (14) | (since C++20)
`std::basic_string` and `std::sub_match` |  |
template< class BidirIt, class Traits, class Alloc > bool operator==( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (15) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator!=( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (16) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator<( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (17) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator<=( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (18) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator>( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (19) | (since C++11) (until C++20)
template< class BidirIt, class Traits, class Alloc > bool operator>=( const std::basic_string< typename std::iterator_traits<BidirIt>::value_type, Traits,Alloc>& st, const std::sub_match<BidirIt>& sm ); | (20) | (since C++11) (until C++20)
`std::sub_match` and `std::iterator_traits<BidirIt>::value_type*` |  |
template< class BidirIt > bool operator==( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (21) | (since C++11)
template< class BidirIt > bool operator!=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (22) | (since C++11) (until C++20)
template< class BidirIt > bool operator<( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (23) | (since C++11) (until C++20)
template< class BidirIt > bool operator<=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (24) | (since C++11) (until C++20)
template< class BidirIt > bool operator>( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (25) | (since C++11) (until C++20)
template< class BidirIt > bool operator>=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (26) | (since C++11) (until C++20)
template< class BidirIt > /*comp-cat*/ operator<=>( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type* s ); | (27) | (since C++20)
`std::iterator_traits<BidirIt>::value_type*` and `std::sub_match` |  |
template< class BidirIt > bool operator==( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (28) | (since C++11) (until C++20)
template< class BidirIt > bool operator!=( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (29) | (since C++11) (until C++20)
template< class BidirIt > bool operator<( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (30) | (since C++11) (until C++20)
template< class BidirIt > bool operator<=( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (31) | (since C++11) (until C++20)
template< class BidirIt > bool operator>( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (32) | (since C++11) (until C++20)
template< class BidirIt > bool operator>=( const typename std::iterator_traits<BidirIt>::value_type* s, const std::sub_match<BidirIt>& sm ); | (33) | (since C++11) (until C++20)
`std::sub_match` and `std::iterator_traits<BidirIt>::value_type` |  |
template< class BidirIt > bool operator==( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (34) | (since C++11)
template< class BidirIt > bool operator!=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (35) | (since C++11) (until C++20)
template< class BidirIt > bool operator<( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (36) | (since C++11) (until C++20)
template< class BidirIt > bool operator<=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (37) | (since C++11) (until C++20)
template< class BidirIt > bool operator>( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (38) | (since C++11) (until C++20)
template< class BidirIt > bool operator>=( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (39) | (since C++11) (until C++20)
template< class BidirIt > /*comp-cat*/ operator<=>( const std::sub_match<BidirIt>& sm, const typename std::iterator_traits<BidirIt>::value_type& ch ); | (40) | (since C++20)
`std::iterator_traits<BidirIt>::value_type` and `std::sub_match` |  |
template< class BidirIt > bool operator==( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (41) | (since C++11) (until C++20)
template< class BidirIt > bool operator!=( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (42) | (since C++11) (until C++20)
template< class BidirIt > bool operator<( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (43) | (since C++11) (until C++20)
template< class BidirIt > bool operator<=( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (44) | (since C++11) (until C++20)
template< class BidirIt > bool operator>( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (45) | (since C++11) (until C++20)
template< class BidirIt > bool operator>=( const typename std::iterator_traits<BidirIt>::value_type& ch, const std::sub_match<BidirIt>& sm ); | (46) | (since C++11) (until C++20)

Compares a `sub_match` to another `sub_match`, a string, a null-terminated character sequence or a character.

1-7) Compares two sub_match directly by comparing their underlying character sequences. Implemented as if by lhs.compare(rhs)
8-20) Compares a sub_match with a std::basic_string. Implemented as if by sm.compare(typename sub_match<BidirIt>::string_type(st.data(), st.size()).
21-33) Compares a sub_match with a null-terminated string. Implemented as if by sm.compare(s).
34-46) Compares a sub_match with a character. Implemented as if by sm.compare(typename sub_match<BidirIt>::string_type(1, ch)).

The return type of three-way comparison operators (/*comp-cat*/) is std::compare_three_way_result_t<typename std::sub_match<BidirIt>::string_type>>, i.e. std::char_traits<typename std::iterator_traits<BidirIt>::value_type>::comparison_category if that qualified-id is valid and denotes a type, std::weak_ordering otherwise. If /*comp-cat*/ is not a comparison category type, the program is ill-formed. The `<`, `<=`, `>`, `>=`, and `!=` operators are synthesized from operator<=> and operator== respectively. | (since C++20)

### Parameters

lhs, rhs, sm | - | a `sub_match` to compare
st | - | a `basic_string` to compare
s | - | a pointer to a null-terminated string to compare
ch | - | a character to compare

### Return value

For `operator==`, (since C++20)true if the corresponding comparison holds as defined by std::sub_match::compare(), false otherwise.

For `operator<=>`, static_cast</*comp-cat*/>(/*comp-res*/ <=> 0), where /*comp-res*/ is the result of std::sub_match::compare() described above. | (since C++20)

### Notes

If value type of `BidirIt` is char, wchar_t, char8_t, char16_t, or char32_t, the return type of `operator<=>` is std::strong_ordering. | (since C++20)

### Example

| This section is incomplete Reason: no example

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 3432 | C++20 | the return type of `operator<=>` was not required to be a comparison category type | required

### See also

compare | compares matched subsequence (if any) (public member function)

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