std::wcstof, std::wcstod, std::wcstold

 

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Null-terminated wide strings

Functions
Character classification
iswalnum iswalpha iswlower iswupper iswdigit iswxdigit wctype	iswblank (C++11) iswctype iswcntrl iswgraph iswspace iswprint iswpunct
Character manipulation
towlower towupper	towctrans wctrans
Conversions to numeric formats
wcstolwcstoll (C++11)   wcstofwcstodwcstold (C++11)(C++11)	wcstoulwcstoull (C++11) wcstoimaxwcstouimax (C++11)(C++11)
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wcslen wcscmp wcscoll wcsncmp wcschr wcsrchr	wcspbrk wcsspn wcscspn wcsstr wcstok
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wcscpy wcsncpy wcsxfrm	wcscat wcsncat
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Types wctrans_t wctype_t wint_t	Macros WCHAR_MIN WCHAR_MAX WEOF

 

Defined in header <cwchar>
float       wcstof(constwchar_t* str, wchar_t** str_end );		(since C++11)
double      wcstod(constwchar_t* str, wchar_t** str_end );
longdouble wcstold(constwchar_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 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)e or E followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 10)

hexadecimal floating-point expression. It consists of the following parts: (optional) plus or minus sign 0x or 0X nonempty sequence of hexadecimal digits optionally containing a decimal-point character (as determined by the current C locale) (defines significand) (optional)p or P followed with optional minus or plus sign and nonempty sequence of decimal digits (defines exponent to base 2) infinity expression. It consists of the following parts: (optional) plus or minus sign INF or INFINITY ignoring case not-a-number expression. It consists of the following parts: (optional) plus or minus sign NAN or NAN(char_sequence ) ignoring case of the NAN part. char_sequence can only contain digits, Latin letters, and underscores. The result is a quiet NaN floating-point value.

(since C++11)

• 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 a null pointer, it is ignored.

Parameters

str	-	pointer to the null-terminated 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

Run this code

#include <cerrno>#include <clocale>#include <cwchar>#include <iostream>#include <string>   int main(){constwchar_t* p = L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 -Inf 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';}   if(std::setlocale(LC_NUMERIC, "de_DE.utf8")){std::wcout<< L"With de_DE.utf8 locale:\n";std::wcout<< L" '123.45' -> "<< std::wcstod(L"123.45", 0)<< L'\n';std::wcout<< L" '123,45' -> "<< std::wcstod(L"123,45", 0)<< L'\n';}}

Output:

Parsing L"111.11 -2.22 0X1.BC70A3D70A3D7P+6 -Inf 1.18973e+4932zzz": '111.11' -> 111.11 ' -2.22' -> -2.22 ' 0X1.BC70A3D70A3D7P+6' -> 111.11 ' -Inf' -> -inf ' 1.18973e+4932' -> range error, got inf With de_DE.utf8 locale: '123.45' -> 123 '123,45' -> 123.45

See also

strtofstrtodstrtold	converts a byte string to a floating-point value (function)
C documentation for wcstof