std::stof, std::stod, std::stold

`<string>`
`float stof( const std::string& str, std::size_t* pos = 0 ); float stof( const std::wstring& str, std::size_t* pos = 0 );`	(1)	(C++11)
`double stod( const std::string& str, std::size_t* pos = 0 ); double stod( const std::wstring& str, std::size_t* pos = 0 );`	(2)	(C++11)
`long double stold( const std::string& str, std::size_t* pos = 0 ); long double stold( const std::wstring& str, std::size_t* pos = 0 );`	(3)	(C++11)

str

1) `std::strtod(str.c_str(), &ptr)` `std::wcstod(str.c_str(), &ptr)`	(C++17)
1) `std::strtof(str.c_str(), &ptr)` `std::wcstof(str.c_str(), &ptr)`	(C++17)

2) std::strtod(str.c_str(), &ptr) std::wcstod(str.c_str(), &ptr)

3) std::strtold(str.c_str(), &ptr) std::wcstold(str.c_str(), &ptr)

( std::isspace() )

pos ptr () str.c_str() *pos

str	-
pos	-

(strtof (C++17)strtod strtold) errno ERANGE std::out_of_range