std::stof
std::stof, std::stod, std::stold
| Defined in header | | |
|---|---|---|
| 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.
| 1) calls std::strtod(str.c_str(), &ptr) or std::wcstod(str.c_str(), &ptr) | (until C++17) |
|---|---|
| 1) calls std::strtof(str.c_str(), &ptr) or std::wcstof(str.c_str(), &ptr) | (since C++17) |
2) calls std::strtod(str.c_str(), &ptr) or std::wcstod(str.c_str(), &ptr)
3) calls std::strtold(str.c_str(), &ptr) or 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:
If pos is not a null pointer, then a pointer ptr, internal to the conversion functions, 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 (strtof, (since C++17)strtod or strtold) sets errno to ERANGE.
See also
| stoistolstoll (C++11)(C++11)(C++11) | converts a string to a signed integer (function) |
|---|---|
| stoulstoull (C++11)(C++11) | converts a string to an unsigned integer (function) |
| from_chars (C++17) | converts a character sequence to an integer or floating-point value (function) |
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