WCSTOUL(3POSIX)

💖 WCSTOUL(3POSIX) 💖

okay so this page is straight out of the POSIX Programmer's Manual, and we are going to read it together like the little study buddies we are. grab a boba. 🧋

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🌸 PROLOG 🌸

okay bestie, real talk before we even start: this manual page is part of the POSIX Programmer's Manual. but heads up — the Linux implementation of this interface may differ (so go consult the corresponding Linux manual page for the details of Linux behavior, k?), or honestly the interface may just not be implemented on Linux at all. 🙈

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🦋 NAME 🦋

wcstoul, wcstoull — convert a wide-character string to an unsigned long. that's the whole vibe, that's the whole job. ✨

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🎀 SYNOPSIS 🎀

#include <wchar.h>

unsigned long wcstoul(const wchar_t *restrict nptr,
    wchar_t **restrict endptr, int base);
unsigned long long wcstoull(const wchar_t *restrict nptr,
    wchar_t **restrict endptr, int base);

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👑 DESCRIPTION 👑

first things first, the lore: the functionality described on this reference page is aligned with the ISO C standard. any conflict between the requirements described here and the ISO C standard is unintentional — nobody's trying to start drama. this volume of POSIX.1‐2017 defers to the ISO C standard. periodt. 💅

so the wcstoul() and wcstoull() functions shall convert the initial portion of the wide-character string pointed to by nptr to unsigned long and unsigned long long representation, respectively. and how do they do it? they decompose the input wide-character string into three parts, like a little three-step skincare routine:

1. An initial, possibly empty, sequence of white-space wide-character codes (as specified by iswspace())
2. A subject sequence interpreted as an integer represented in some radix determined by the value of base
3. A final wide-character string of one or more unrecognized wide-character codes, including the terminating null wide-character code of the input wide-character string

then they shall attempt to convert the subject sequence to an unsigned integer, and return the result. slay. 🌈

now, if base is 0, the expected form of the subject sequence is that of a decimal constant, an octal constant, or a hexadecimal constant, any of which may be preceded by a '+' or '-' sign. a decimal constant begins with a non-zero digit, and consists of a sequence of decimal digits. an octal constant consists of the prefix '0' optionally followed by a sequence of the digits '0' to '7' only. a hexadecimal constant consists of the prefix 0x or 0X followed by a sequence of the decimal digits and letters 'a' (or 'A') to 'f' (or 'F') with values 10 to 15 respectively. iconic behavior honestly.

if the value of base is between 2 and 36, the expected form of the subject sequence is a sequence of letters and digits representing an integer with the radix specified by base, optionally preceded by a '+' or '-' sign, but not including an integer suffix. the letters from 'a' (or 'A') to 'z' (or 'Z') inclusive are ascribed the values 10 to 35; only letters whose ascribed values are less than that of base shall be permitted. and if the value of base is 16, the wide-character codes 0x or 0X may optionally precede the sequence of letters and digits, following the sign if present. ✨

the subject sequence is defined as the longest initial subsequence of the input wide-character string, starting with the first wide-character code that is not white space and is of the expected form. and listen — the subject sequence contains no wide-character codes if the input wide-character string is empty, or consists entirely of white-space wide-character codes, or if the first wide-character code that is not white space is other than a sign or a permissible letter or digit. basically if there's nothing to convert, bestie, there's nothing to convert. 💀

if the subject sequence has the expected form and base is 0, the sequence of wide-character codes starting with the first digit shall be interpreted as an integer constant. if the subject sequence has the expected form and the value of base is between 2 and 36, it shall be used as the base for conversion, ascribing to each letter its value as given above. if the subject sequence begins with a <hyphen-minus>, the value resulting from the conversion shall be negated. a pointer to the final wide-character string shall be stored in the object pointed to by endptr, provided that endptr is not a null pointer.

in other than the C or POSIX locale, additional locale-specific subject sequence forms may be accepted. (localized slay 💅)

if the subject sequence is empty or does not have the expected form, no conversion shall be performed; the value of nptr shall be stored in the object pointed to by endptr, provided that endptr is not a null pointer.

these functions shall not change the setting of errno if successful. so don't go blaming them for anything, okay?

and this part is IMPORTANT so put your phone down: since 0, {ULONG_MAX}, and {ULLONG_MAX} are returned on error and 0 is also a valid return on success, an application wishing to check for error situations should set errno to 0, then call wcstoul() or wcstoull(), then check errno. that's the whole trick. don't skip it. 🫶

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💜 RETURN VALUE 💜

upon successful completion, the wcstoul() and wcstoull() functions shall return the converted value, if any. if no conversion could be performed, 0 shall be returned and errno may be set to indicate the error. if the correct value is outside the range of representable values, {ULONG_MAX} or {ULLONG_MAX} respectively shall be returned and errno set to [ERANGE]. 😭

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😭 ERRORS 😭

these functions shall fail if:

• EINVAL — the value of base is not supported.
• ERANGE — the value to be returned is not representable.

these functions may fail if:

• EINVAL — no conversion could be performed.

the following sections are informative. (so like, take them as lore and not law, bestie. 💅)

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✨ EXAMPLES ✨

None. yes really, it just says None. the example section said "not today." 🙈

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🌟 APPLICATION USAGE 🌟

None. also empty. the girlies are resting. 😴

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🧚 RATIONALE 🧚

None. still empty. we love a minimal moment. 💜

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⭐ FUTURE DIRECTIONS ⭐

None. the future is a mystery, and this section is choosing peace. ✨

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🫶 SEE ALSO 🫶

• fscanf(), iswalpha(), wcstod(), wcstol()
• The Base Definitions volume of POSIX.1‐2017, <wchar.h>

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📜 COPYRIGHT 📜

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the page, bestie!! 🎀 it's signed off by IEEE/The Open Group, dated 2017. go forth and convert those wide-character strings responsibly. mwah. 💖👑🦋