operator==,!=,<,<=,>,>=,<=>(std::basic_string) - cppreference.com

Compare two basic_string objects

template< class CharT, class Traits, class Alloc >
bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(1) (noexcept since C++11)
(constexpr since C++20)

template< class CharT, class Traits, class Alloc >
bool operator!=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(2) (until C++20)
(noexcept since C++11)

template< class CharT, class Traits, class Alloc >
bool operator<( const std::basic_string<CharT,Traits,Alloc>& lhs,
                const std::basic_string<CharT,Traits,Alloc>& rhs );

(3) (until C++20)
(noexcept since C++11)

template< class CharT, class Traits, class Alloc >
bool operator<=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(4) (until C++20)
(noexcept since C++11)

template< class CharT, class Traits, class Alloc >
bool operator>( const std::basic_string<CharT,Traits,Alloc>& lhs,
                const std::basic_string<CharT,Traits,Alloc>& rhs );

(5) (until C++20)
(noexcept since C++11)

template< class CharT, class Traits, class Alloc >
bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(6) (until C++20)
(noexcept since C++11)

template< class CharT, class Traits, class Alloc >
constexpr /*comp-cat*/
    operator<=>( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs ) noexcept;

(7) (since C++20)

Compare a basic_string object and null-terminated array of T

template< class CharT, class Traits, class Alloc >
bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const CharT* rhs );

(8) (constexpr since C++20)

template< class CharT, class Traits, class Alloc >
bool operator==( const CharT* lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(9) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator!=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const CharT* rhs );

(10) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator!=( const CharT* lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(11) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator<( const std::basic_string<CharT,Traits,Alloc>& lhs,
                const CharT* rhs );

(12) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator<( const CharT* lhs,
                const std::basic_string<CharT,Traits,Alloc>& rhs );

(13) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator<=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const CharT* rhs );

(14) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator<=( const CharT* lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(15) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator>( const std::basic_string<CharT,Traits,Alloc>& lhs,
                const CharT* rhs );

(16) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator>( const CharT* lhs,
                const std::basic_string<CharT,Traits,Alloc>& rhs );

(17) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const CharT* rhs );

(18) (until C++20)

template< class CharT, class Traits, class Alloc >
bool operator>=( const CharT* lhs,
                 const std::basic_string<CharT,Traits,Alloc>& rhs );

(19) (until C++20)

template< class CharT, class Traits, class Alloc >
constexpr /*comp-cat*/
    operator<=>( const std::basic_string<CharT,Traits,Alloc>& lhs,
                 const CharT* rhs );

(20) (since C++20)

Compares the contents of a string with another string or a null-terminated array of CharT.

All comparisons are done via the compare() member function (which itself is defined in terms of Traits::compare()):

1-7) Compares two basic_string objects.

8-20) Compares a basic_string object and a null-terminated array of CharT.

1-6,8-19) true if the corresponding comparison holds, false otherwise.

7,20) static_cast</*comp-cat*/>(lhs.compare(rhs) <=> 0).

Linear in the size of the strings.

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