strstream(); (1) strstream(char* s, int n, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out); (2) Constructs new input/output strstream and its underlying std::strstreambuf. 1) Default-constructs the underlying std::strstreambuf, which creates a dynamically growing buffer, and initializes the base class with the address of the strstreambuf member. 2) Initialized the base class with the address of the underlying std::strstreambuf me

Defined in header <ios> template< class CharT, class Traits = std::char_traits<CharT> > class basic_ios : public ios_base The class std::basic_ios provides facilities for interfacing with objects that have std::basic_streambuf interface. Several std::basic_ios objects can refer to one actual std::basic_streambuf object. Inheritance diagram. Two specializations for common character types are also provided: Type Definition ios basic_ios<c

Usage declaration of a union type If a function or a variable exists in scope with the name identical to the name of a union type, union can be prepended to the name for disambiguation, resulting in an elaborated type specifier

(1) bool operator[]( std::size_t pos ) const; (until C++11) constexpr bool operator[]( std::size_t pos ) const; (since C++11) reference operator[]( std::size_t pos ); (2) Accesses the bit at position pos. The first version returns the value of the bit, the second version returns an object of type std::bitset::reference that allows modification of the value. Unlike test(), does not throw exceptions: the behavior is undefined if pos is out of bounds. Parameters pos - p

Defined in header <cstdlib> int rand(); Returns a pseudo-random integral value between ​0​ and RAND_MAX (0 and RAND_MAX included). std::srand() seeds the pseudo-random number generator used by rand(). If rand() is used before any calls to srand(), rand() behaves as if it was seeded with srand(1). Each time rand() is seeded with srand(), it must produce the same sequence of values on successive calls. Other functions in the standard library may call rand, it is implementatio

Type alias is a name that refers to a previously defined type (similar to typedef). Alias template is a name that refers to a family of types. Syntax Alias declarations are declarations with the following syntax. using identifier attr(optional) = type-id ; (1) template < template-parameter-list > using identifier attr(optional) = type-id ; (2) attr(C++11) - optional sequence of any number of attributes identifier - the name that is introduced by this declaratio

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 <type_traits> template< class T > struct is_scalar; (since C++11) If T is a scalar type (that is, arithmetic type, enumeration type, pointer, pointer to member, or std::nullptr_t, including any cv-qualified variants), provides the member constant value equal true. For any other type, value is false. Template parameters T - a type to check Helper variable template template< class T > constexpr bool is_scalar_v = is_scalar<T&g

template< class BidirIt, class CharT = typename std::iterator_traits<BidirIt>::value_type, class Traits = std::regex_traits<CharT> > class regex_iterator (since C++11) std::regex_iterator is a read-only ForwardIterator that accesses the individual matches of a regular expression within the underlying character sequence. On construction, and on every increment, it calls std::regex_search and remembers the result (that is, saves a copy of the value std::match

Usage decltype specifier decltype(auto) (since C++14)