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

From cppreference.com
< cpp‎ | string‎ | basic string
 
 
 
std::basic_string
 
Defined in header <string>
float       stof( const std::string& str, size_t *pos = 0 );
(1) (since C++11)
double      stod( const std::string& str, size_t *pos = 0 );
(2) (since C++11)
long double stold( const std::string& str, size_t *pos = 0 );
(3) (since C++11)

Interprets a floating point value in a string str.

1) calls std::strtod(str.c_str(), pos)
2) calls std::strtod(str.c_str(), pos)
3) calls std::strtold(str.c_str(), pos)

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 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 a decimal point character (defines significand)
  • (optional) e or E followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
  • binary 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 (defines significand)
  • (optional) p or P followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
  • 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 alphanumeric characters. The result is a quiet NaN floating point value.

The index of the first unconverted character is stored in pos. If NULL is passed as pos, it is ignored.

Contents

[edit] Parameters

str - the string to convert
pos - address of integer to store the index of the first unconverted character

[edit] Return value

The string converted to the specified floating point type.

[edit] 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 (strtod or strtold) sets errno to ERANGE.

[edit] See also

(C++11)(C++11)(C++11)
converts a string to a signed integer
(function) [edit]
(C++11)(C++11)
converts a string to an unsigned integer
(function) [edit]