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::iswspace()) until first nonwhitespace character is found. Then it takes as many characters as possible to form a valid floatingpoint representation and converts them to a floatingpoint value. The valid floatingpoint value can be one of the following:
 decimal floatingpoint expression. It consists of the following parts:
 (optional) plus or minus sign
 nonempty sequence of decimal digits optionally containing decimalpoint character (as determined by the current C locale) (defines significand)
 (optional)
e
orE
followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent)
 binary floatingpoint expression. It consists of the following parts:
 (optional) plus or minus sign

0x
or0X
 nonempty sequence of hexadecimal digits optionally containing a decimalpoint character (as determined by the current C locale) (defines significand)
 (optional)
p
orP
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
orINFINITY
ignoring case
 notanumber 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 floatingpoint 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.
Parameters
str    pointer to the nullterminated wide string to be interpreted 
str_end    pointer to a pointer to a wide character. 
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.
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, endp) << "' > "; 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
See also
converts a byte string to a floating point value (function) 