std::wcstof, std::wcstod, std::wcstold
| Defined in header  <cwchar> | ||
| float       wcstof( const wchar_t* str, wchar_t** str_end ); | (since C++11) | |
| double      wcstod( const wchar_t* str, wchar_t** str_end ); | ||
| long double wcstold( const wchar_t* str, wchar_t** str_end ); | (since C++11) | |
Interprets a floating point value in a wide string pointed to by 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 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) 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
The functions sets the pointer pointed to by str_end to point to the wide character past the last character interpreted. If str_end is NULL, it is ignored.
| Contents | 
[edit] Parameters
| str | - | pointer to the null-terminated wide string to be interpreted | 
| str_end | - | pointer to a pointer to a wide character. | 
[edit] Return value
Floating point value corresponding to the contents of str on success. If the converted value falls out of range of corresponding return type, range error occurs and HUGE_VAL, HUGE_VALF or HUGE_VALL is returned. If no conversion can be performed, 0 is returned.
[edit] Example
#include <iostream> #include <string> #include <cerrno> #include <cwchar> int main() { const wchar_t* p = L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz"; wchar_t* end; std::wcout << "Parsing L\"" << p << "\":\n"; for (double f = std::wcstod(p, &end); p != end; f = std::wcstod(p, &end)) { std::wcout << "'" << std::wstring(p, end-p) << "' -> "; p = end; if (errno == ERANGE){ std::wcout << "range error, got "; errno = 0; } std::wcout << f << '\n'; } }
Output:
Parsing L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz": '111.11' -> 111.11 ' -2.22' -> -2.22 ' 0X1.BC70A3D70A3D7P+6' -> 111.11 ' 1.18973e+4932' -> range error, got inf
[edit] See also
| converts a byte string to a floating point value (function) | |
| C documentation for wcstof | |


