wcstod32() - wcstod64() - wcstod128() — Convert Wide-Character String to Decimal Floating-Point

Format

#define __STDC_WANT_DEC_FP__
#include <wchar.h>
_Decimal32 wcstod32(const wchar_t *nptr, wchar_t **endptr);
_Decimal64 wcstod64(const wchar_t *nptr, wchar_t **endptr);
_Decimal128 wcstod128(const wchar_t *nptr, wchar_t **endptr);

Language Level

XPG4

Threadsafe

Yes

Locale Sensitive

The behavior of these functions might be affected by the LC_CTYPE and LC_NUMERIC categories of the current locale if LOCALETYPE(*LOCALE) is specified on the compilation command. The behavior of these functions might also be affected by the LC_UNI_CTYPE and LC_UNI_NUMERIC categories of the current locale if LOCALETYPE(*LOCALEUCS2) or LOCALETYPE(*LOCALEUTF) is specified on the compilation command. These functions are not available when LOCALETYPE(*CLD) is specified on the compilation command. For more information, see Understanding CCSIDs and Locales.

Wide Character Function

See Wide Characters for more information.

Description

The wcstod32(), wcstod64(), and wcstod128() functions convert the initial portion of the wide-character string pointed to by nptr to a single-precision, double-precision, or quad-precision decimal floating-point value. The parameter nptr points to a sequence of characters that can be interpreted as a numeric decimal floating-point value. The wcstod32(), wcstod64(), and wcstod128() functions stop reading the string at the first character that is not recognized as part of a number. This character can be the wchar_t null character at the end of the string. The endptr parameter is updated to point to this character, provided that endptr is not a NULL pointer.

The wcstod32(), wcstod64(), and wcstod128() functions expect nptr to point to a string with the following form:

The first character that does not fit this form stops the scan. In addition, a sequence of INFINITY or NAN (ignoring case) is allowed.

Return Value

The wcstod32(), wcstod64(), and wcstod128() functions return the value of the floating-point number, except when the representation causes an underflow or overflow. For an overflow, wcstod32() returns HUGE_VAL_D32 or -HUGE_VAL_D32; wcstod64() returns HUGE_VAL_D64 or -HUGE_VAL_D64; wcstod128() returns HUGE_VAL_D128 or -HUGE_VAL_D128. For an underflow, all functions return +0.E0.

In both the overflow and underflow cases, errno is set to ERANGE. If the string pointed to by nptr does not have the expected form, a value of +0.E0 is returned and the value of nptr is stored in the object pointed to by endptr, provided that endptr is not a NULL pointer.

The wcstod32(), wcstod64(), and wcstod128() functions do not fail if a character other than a digit follows an E or e that is read as an exponent. For example, 100elf is converted to the floating-point value 100.0.

A character sequence of INFINITY (ignoring case) yields a value of INFINITY. A character value of NAN (ignoring case) yields a Quiet Not-A-Number (NaN) value.

If necessary, the return value is rounded using the rounding mode Round to Nearest, Ties to Even.

Example

This example converts the string wcs to single-precision, double-precision, and quad-precision decimal floating-point values.

#define __STDC_WANT_DEC_FP__
#include <stdio.h>
#include <wchar.h>
 
int main(void)
{
   wchar_t *wcs = L"3.1415926This stopped it";
   wchar_t *stopwcs;
 
   printf("wcs = \"%ls\"\n", wcs);
   printf("wcstod32 = %Hf\n", wcstod32(wcs, &stopwcs));
   printf(" Stopped scan at \"%ls\"\n", stopwcs); 
   printf("wcs = \"%ls\"\n", wcs);
   printf("wcstod64 = %Df\n", wcstod64(wcs, &stopwcs));
   printf(" Stopped scan at \"%ls\"\n", stopwcs);
   printf("wcs = \"%ls\"\n", wcs);
   printf("wcstod128 = %DDf\n", wcstod128(wcs, &stopwcs));
   printf(" Stopped scan at \"%ls\"\n", stopwcs);
}

/***************** Output should be similar to: *****************


wcs = "3.1415926This stopped it"
wcstod32 = 3.141593
 Stopped scan at "This stopped it"
wcs = "3.1415926This stopped it"
wcstod64 = 3.141593
 Stopped scan at "This stopped it"
wcs = "3.1415926This stopped it"
wcstod128 = 3.141593
 Stopped scan at "This stopped it"

*/