operator==,!=,<,<=,>,>=,<=>(std::basic_string)

Since C++20

Header: <string>

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

# Declarations

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 );

(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 );

(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 );

(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 );

(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 );

(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 );

(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;

(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 );

(constexpr since C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(until C++20)

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

(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 );

(since C++20)

# Parameters

lhs, rhs: strings whose contents to compare

# Notes

If at least one parameter is of type std::string, std::wstring, std::u8string, std::u16string, or std::u32string, the return type of operator<=> is std::strong_ordering.

# Example

This section is incompleteReason: no example

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 2064	C++11	whether overloads taking two basic_strings are noexcept was inconsistent;overloads taking a CharT* were noexcept but might raise UB	made consistent;noexcept removed
LWG 3432	C++20	the return type of operator<=> was not required to be a comparison category type	required