virtual std::string message( int condition ) const = 0; (since C++11) Returns a string describing the given error condition for the error category represented by *this. Parameters condition - specifies the error condition to describe Return value A string describing the given error condition. Exceptions (none).

error_category( const error_category& other ) = delete; (1) (since C++11) constexpr error_category(); (2) (since C++14) Constructs the error category object. Parameters (none). Exceptions 2) noexcept specification: noexcept

virtual bool equivalent( int code, const std::error_condition& condition ) const; (1) (since C++11) virtual bool equivalent( const std::error_code& code, int condition ) const; (2) (since C++11) Checks whether error code is equivalent to an error condition for the error category represented by *this. 1) Equivalent to default_error_condition(code) == condition. 2) Equivalent to *this == code.category() && code.val

virtual std::error_condition default_error_condition( int code ) const; (since C++11) Returns the error condition for the given error code. Equivalent to std::error_condition(code, *this). Parameters code - error code for which to return error condition Return value The error condition for the given error code. Exceptions noexcept specification: noexcept

Defined in header <system_error> class error_category; (since C++11) std::error_category serves as the base class for specific error category types, such as std::system_category, std::iostream_category, etc. Each specific category class defines the error_code - error_condition mapping and holds the explanatory strings for all error_conditions. The objects of error category classes are treated as singletons, passed by reference. Member functions (constructor) construc

Defined in header <system_error> enum class errc; (since C++11) The scoped enumeration std::errc defines the values of portable error conditions that correspond to the POSIX error codes. Member constants Constant Explanation address_family_not_supported error condition corresponding to POSIX code EAFNOSUPPORT address_in_use error condition corresponding to POSIX code EADDRINUSE address_not_available error condition corresponding to POSIX code EADDRNOTAVAIL

Defined in header <cmath> float erfc( float arg ); (1) (since C++11) double erfc( double arg ); (2) (since C++11) long double erfc( long double arg ); (3) (since C++11) double erfc( Integral arg ); (4) (since C++11) 1-3) Computes the complementary error function of arg, that is 1.0-erf(arg), but without loss of precision for large arg 4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2

Defined in header <cmath> float erf( float arg ); (1) (since C++11) double erf( double arg ); (2) (since C++11) long double erf( long double arg ); (3) (since C++11) double erf( Integral arg ); (4) (since C++11) 1-3) Computes the error function of arg. 4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to double). Parameters arg - value of a floating-poin

Defined in header <functional> template<> class equal_to<void>; (since C++14) std::equal_to<> is a specialization of std::equal_to with parameter and return type deduced. Member types Member type Definition is_transparent /* unspecified */ Member functions operator() tests if the two arguments compare equal (public member function) std::equal_to<>::operator() template< class T, class U> constexpr auto operator()( T&

Defined in header <functional> template< class T > struct equal_to; (until C++14) template< class T = void > struct equal_to; (since C++14) Function object for performing comparisons. Unless specialised, invokes operator== on type T. Specializations The standard library provides a specialization of std::equal_to when T is not specified, which leaves the parameter types and return type to be deduced. equal_to<void> function object implementing