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

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[edit]

std::basic_string

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swap(std::basic_string)

erase(std::basic_string)erase_if(std::basic_string)

(C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=>

(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Numeric conversions

stoistolstoll (C++11)(C++11)(C++11)
stoulstoull (C++11)(C++11)

stofstodstold (C++11)(C++11)(C++11)
to_string (C++11)
to_wstring (C++11)

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operator""s

(C++14)

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hash<std::basic_string>

(C++11)

Deduction guides(C++17)

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Defined in header`<string>`
float stof(conststd::string& str,std::size_t* pos= nullptr);	(1)	(since C++11)
float stof(conststd::wstring& str,std::size_t* pos= nullptr);	(2)	(since C++11)
double stod(conststd::string& str,std::size_t* pos= nullptr);	(3)	(since C++11)
double stod(conststd::wstring& str,std::size_t* pos= nullptr);	(4)	(since C++11)
longdouble stold(conststd::string& str,std::size_t* pos= nullptr);	(5)	(since C++11)
longdouble stold(conststd::wstring& str,std::size_t* pos= nullptr);	(6)	(since C++11)

Interprets a floating point value in a stringstr.

Letptr be an internal (to the conversion functions) pointer of typechar*(1,3,5) orwchar_t*(2,4,6), accordingly.

1) Callsstd::strtof(str.c_str(),&ptr).

2) Callsstd::wcstof(str.c_str(),&ptr).

3) Callsstd::strtod(str.c_str(),&ptr).

4) Callsstd::wcstod(str.c_str(),&ptr).

5) Callsstd::strtold(str.c_str(),&ptr).

6) Callsstd::wcstold(str.c_str(),&ptr).

Function discards any whitespace characters (as determined bystd::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 Clocale) (defines significand)
(optional)e orE followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base10)

hexadecimal floating-point expression. It consists of the following parts:

(optional) plus or minus sign
0x or0X
nonempty sequence of hexadecimal digits optionally containing a decimal-point character (as determined by the current Clocale) (defines significand)
(optional)p orP followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base2)

infinity expression. It consists of the following parts:

(optional) plus or minus sign
INF orINFINITY ignoring case

not-a-number expression. It consists of the following parts:

(optional) plus or minus sign
NAN orNAN(char_sequence ) ignoring case of theNAN 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 Clocale.

Ifpos is not a null pointer, thenptr will receive the address of the first unconverted character instr.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.

[edit]Parameters

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

[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 (std::strtof,std::strtod orstd::strtold) setserrno toERANGE.

[edit]Example

This section is incomplete
Reason: no example

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2009	C++11	std::out_of_range would not be thrown if the converted value would fall out of the range of the result type	will throw
LWG 2403	C++11	`stof` calledstd::strtod orstd::wcstod	`stof` callsstd::strtof orstd::wcstof

[edit]See also

stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)[edit]
stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)[edit]
from_chars (C++17)	converts a character sequence to an integer or floating-point value (function)[edit]