std::char_traits<char>::eq/lt,std::char_traits<wchar_t>::eq/lt,std::char_traits<char8_t>::eq/lt,std::char_traits<char16_t>::eq/lt,std::char_traits<char32_t>::eq/lt

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staticbool eq( char_type a, char_type b);	(1)	(constexpr since C++11) (noexcept since C++11)
staticbool lt( char_type a, char_type b);	(2)	(constexpr since C++11) (noexcept since C++11)

Compares two characters.

1) Comparesa andb for equality, behaves identically to

static_cast<unsignedchar>(a)==static_cast<unsignedchar>(b), ifchar_type ischar,
a== b otherwise.

2) Comparesa andb in such a way that they are totally ordered, behaves identically to

static_cast<unsignedchar>(a)<static_cast<unsignedchar>(b), ifchar_type ischar,
a< b otherwise.

SeeCharTraits for the general requirements on character traits forX::eq andX::lt.

a, b

character values to compare

1)true ifa andb are equal,false otherwise.

2)true ifa is less thanb,false otherwise.

Constant.

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

DR	Applied to	Behavior as published	Correct behavior
LWG 467	C++98	forstd::char_traits<char>, the semantics of`eq()` and`lt()` are the same as the built-in== and< onchar respectively^[1]	changed to built-in== and < onunsignedchar

↑Most implementations callstd::memcmp() for efficiency, which interprets the data as arrays ofunsignedchar. Ifcharis signed on such implementations,std::char_traits<char> fails to satisfy the requirements ofCharTraits.

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