std::stof,std::stod,std::stold(3)

NAME
std::stof,std::stod,std::stold - std::stof,std::stod,std::stold

Synopsis
   Defined in header <string>
   float stof ( const std::string& str, std::size_t* pos = (1) (since C++11)
   nullptr );
   float stof ( const std::wstring& str, std::size_t* pos = (2) (since C++11)
   nullptr );
   double stod ( const std::string& str, std::size_t* pos = (3) (since C++11)
   nullptr );
   double stod ( const std::wstring& str, std::size_t* pos = (4) (since C++11)
   nullptr );
   long double stold( const std::string& str, std::size_t* pos = (5) (since C++11)
   nullptr );
   long double stold( const std::wstring& str, std::size_t* pos = (6) (since C++11)
   nullptr );
   Interprets a floating point value in a string str.
   Let ptr be an internal (to the conversion functions) pointer of type char* (1,3,5)
   or wchar_t* (2,4,6), accordingly.
   1) Calls std::strtof(str.c_str(), &ptr).
   2) Calls std::wcstof(str.c_str(), &ptr).
   3) Calls std::strtod(str.c_str(), &ptr).
   4) Calls std::wcstod(str.c_str(), &ptr).
   5) Calls std::strtold(str.c_str(), &ptr).
   6) Calls std::wcstold(str.c_str(), &ptr).
   Function discards any whitespace characters (as determined by std::isspace) until
   first non-whitespace character is found. Then it takes as many characters as
   possible to form a valid floating-point representation and converts them to a
   floating-point value. The valid floating-point value can be one of the following:
     * decimal floating-point expression. It consists of the following parts:
     * (optional) plus or minus sign
     * nonempty sequence of decimal digits optionally containing decimal-point
       character (as determined by the current C locale) (defines significand)
     * (optional) e or E followed with optional minus or plus sign and nonempty
       sequence of decimal digits (defines exponent to base 10)
     * hexadecimal floating-point expression. It consists of the following parts:
     * (optional) plus or minus sign
     * 0x or 0X
     * nonempty sequence of hexadecimal digits optionally containing a decimal-point
       character (as determined by the current C locale) (defines significand)
     * (optional) p or P followed with optional minus or plus sign and nonempty
       sequence of decimal digits (defines exponent to base 2)
     * infinity expression. It consists of the following parts:
     * (optional) plus or minus sign
     * INF or INFINITY ignoring case
     * not-a-number expression. It consists of the following parts:
     * (optional) plus or minus sign
     * NAN or NAN(char_sequence) ignoring case of the NAN part. char_sequence can only
       contain digits, Latin letters, and underscores. The result is a quiet NaN
       floating-point value.
     * any other expression that may be accepted by the currently installed C locale
   If pos is not a null pointer, then ptr will receive the address of the first
   unconverted character in str.c_str(), and the index of that character will be
   calculated and stored in *pos, giving the number of characters that were processed
   by the conversion.

Parameters
   str - the string to convert
   pos - address of an integer to store the number of characters processed

Return value
   The string converted to the specified floating point type.

Exceptions
   std::invalid_argument if no conversion could be performed.
   std::out_of_range if the converted value would fall out of the range of the result
   type or if the underlying function (std::strtof, std::strtod or std::strtold) sets
   errno to ERANGE.

Example
    This section is incomplete
    Reason: no example
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
                       std::out_of_range would not be thrown
   LWG 2009 C++11 if the converted will throw
                       value would fall out of the range of
                       the result type
   LWG 2403 C++11 stof called std::strtod or std::wcstod stof calls std::strtof or
                        std::wcstof

See also
   stoi
   stol
   stoll converts a string to a signed integer
   (C++11) (function)
   (C++11)
   (C++11)
   stoul
   stoull converts a string to an unsigned integer
   (C++11) (function)
   (C++11)
   from_chars converts a character sequence to an integer or floating-point value
   (C++17) (function)

Category:
     * Todo no example