wcstof, wcstod, wcstold

 

C

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Concurrency support (哋它亢11)

Technical Specifications

Symbol index

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated wide strings

Functions
Character manipulation
iswalnum (哋它亢95) iswalpha (哋它亢95) iswlower (哋它亢95) iswupper (哋它亢95) iswdigit (哋它亢95) iswxdigit (哋它亢95) iswblank (哋它亢99) wctype (哋它亢95) iswctype (哋它亢95)	iswcntrl (哋它亢95) iswgraph (哋它亢95) iswspace (哋它亢95) iswprint (哋它亢95) iswpunct (哋它亢95) towlower (哋它亢95) towupper (哋它亢95) wctrans (哋它亢95) towctrans (哋它亢95)
Conversions to numeric formats
wcstolwcstoll (哋它亢95)(哋它亢99) wcstoulwcstoull (哋它亢95)(哋它亢99)	wcstofwcstodwcstold (哋它亢99)(哋它亢95)(哋它亢99) wcstoimaxwcstoumax (哋它亢99)(哋它亢99)
String manipulation
wcslenwcsnlen_s (哋它亢95)(哋它亢11) wcscpywcscpy_s (哋它亢95)(哋它亢11) wcsncpywcsncpy_s (哋它亢95)(哋它亢11) wcscatwcscat_s (哋它亢95)(哋它亢11) wcsncatwcsncat_s (哋它亢95)(哋它亢11) wcsstr (哋它亢95)	wcscmp (哋它亢95) wcsncmp (哋它亢95) wcscoll (哋它亢95) wcsxfrm (哋它亢95) wcschr (哋它亢95) wcsrchr (哋它亢95) wcspbrk (哋它亢95) wcsspn (哋它亢95) wcscspn (哋它亢95) wcstokwcstok_s (哋它亢95)(哋它亢11)
Array manipulation
wmemcpywmemcpy_s (哋它亢95)(哋它亢11) wmemmovewmemmove_s (哋它亢95)(哋它亢11)	wmemcmp (哋它亢95) wmemchr (哋它亢95) wmemset (哋它亢95)

 

Defined in header <wchar.h>
float       wcstof( const wchar_t* restrict str, wchar_t** restrict str_end );		(since 哋它亢99)
double      wcstod( const wchar_t* str, wchar_t** str_end );		(since 哋它亢95) (until 哋它亢99)
double      wcstod( const wchar_t* restrict str, wchar_t** restrict str_end );		(since 哋它亢99)
long double wcstold( const wchar_t* restrict str, wchar_t** restrict str_end );		(since 哋它亢99)

Interprets a floating-point value in a wide string pointed to by str.

Function discards any whitespace characters (as determined by 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 哋它亢99)

• 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 <errno.h>
#include <stdio.h>
#include <wchar.h>
 
int main(void)
{
    const wchar_t* p = L"111.11 -2.22 0X1.BC70A3D70A3D7P+6  1.18973e+4932zzz";
    printf("Parsing L\"%ls\":\n", p);
    wchar_t* end;
    for (double f = wcstod(p, &end); p != end; f = wcstod(p, &end))
    {
        printf("'%.*ls' -> ", (int)(end-p), p);
        p = end;
        if (errno == ERANGE){
            printf("range error, got ");
            errno = 0;
        }
        printf("%f\n", f);
    }
}

Output:

Parsing L"111.11 -2.22 0X1.BC70A3D70A3D7P+6  1.18973e+4932zzz":
'111.11' -> 111.110000
' -2.22' -> -2.220000
' 0X1.BC70A3D70A3D7P+6' -> 111.110000
'  1.18973e+4932' -> range error, got inf

References

• 哋它亢23 standard (ISO/IEC 9899:2023):

• 7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: TBD)

• 哋它亢17 standard (ISO/IEC 9899:2018):

• 7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: TBD)

• 哋它亢11 standard (ISO/IEC 9899:2011):

• 7.29.4.1.1 The wcstod, wcstof, and wcstold functions (p: 426-428)

• 哋它亢99 standard (ISO/IEC 9899:1999):

• 7.24.4.1.1 The wcstod, wcstof, and wcstold functions (p: 372-374)

See also

strtofstrtodstrtold (哋它亢99)(哋它亢99)

converts a byte string to a floating-point value (function)