std::stof, std::stod, std::stold
| Defined in header <string>
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| float stof( const std::string& str, std::size_t* pos = 0 ); float stof( const std::wstring& str, std::size_t* pos = 0 ); |
(1) | (since 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) | (since 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) | (since C++11) |
Interprets a floating point value in a string str.
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 decimal point character (as determined by the current C locale) (defines significand)
- (optional)
eorEfollowed 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
-
0xor0X - nonempty sequence of hexadecimal digits optionally containing a decimal point character (as determined by the current C locale) (defines significand)
- (optional)
porPfollowed 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
-
INForINFINITYignoring case
- not-a-number expression. It consists of the following parts:
- (optional) plus or minus sign
-
NANorNAN(char_sequence)ignoring case of theNANpart. char_sequence can only contain alphanumeric characters. 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 passed a value other than 0 or nullptr, then a pointer ptr, internal to the conversion functions, will receive the address of the first unconverted character, and the index of that character will be calculated and stored in *pos.
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) |
| (C++11)(C++11) |
converts a string to an unsigned integer (function) |