langinfo.h(0P)

🦋 langinfo.h(0P) — POSIX Programmer's Manual 🦋

okay bestie, we're reading a POSIX Programmer's Manual page, no cap, and this one is all about the <langinfo.h> header. Buckle up, it's giving lore 💅

---

🎀 PROLOG 🎀

Real talk first: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so go consult the corresponding Linux manual page for details of Linux behavior — or honestly the interface may not even be implemented on Linux at all. 🙈

---

✨ NAME ✨

langinfo.h — language information constants 🫶

---

🌸 SYNOPSIS 🌸

#include <langinfo.h>

---

💖 DESCRIPTION 💖

so the <langinfo.h> header shall define the symbolic constants that identify items of langinfo data (peep nl_langinfo() for that, iykyk).

The <langinfo.h> header shall define the locale_t type as described in <locale.h>.

The <langinfo.h> header shall define the nl_item type as described in <nl_types.h>.

The <langinfo.h> header shall define the following symbolic constants with type nl_item. The entries under Category tell you in which setlocale() category each item is defined. Not me organizing them by category so you don't get lost 💅

🌈 LC_CTYPE girlies

• CODESET (Category: LC_CTYPE) — the codeset name.

⏰ LC_TIME girlies (the big group, she's iconic)

• D_T_FMT — string for formatting date and time.
• D_FMT — date format string.
• T_FMT — time format string.
• T_FMT_AMPM — a.m. or p.m. time format string.
• AM_STR — ante-meridiem affix.
• PM_STR — post-meridiem affix.
• DAY_1 — name of the first day of the week (for example, Sunday).
• DAY_2 — name of the second day of the week (for example, Monday).
• DAY_3 — name of the third day of the week (for example, Tuesday).
• DAY_4 — name of the fourth day of the week (for example, Wednesday).
• DAY_5 — name of the fifth day of the week (for example, Thursday).
• DAY_6 — name of the sixth day of the week (for example, Friday).
• DAY_7 — name of the seventh day of the week (for example, Saturday).
• ABDAY_1 — abbreviated name of the first day of the week.
• ABDAY_2 — abbreviated name of the second day of the week.
• ABDAY_3 — abbreviated name of the third day of the week.
• ABDAY_4 — abbreviated name of the fourth day of the week.
• ABDAY_5 — abbreviated name of the fifth day of the week.
• ABDAY_6 — abbreviated name of the sixth day of the week.
• ABDAY_7 — abbreviated name of the seventh day of the week.
• MON_1 — name of the first month of the year.
• MON_2 — name of the second month.
• MON_3 — name of the third month.
• MON_4 — name of the fourth month.
• MON_5 — name of the fifth month.
• MON_6 — name of the sixth month.
• MON_7 — name of the seventh month.
• MON_8 — name of the eighth month.
• MON_9 — name of the ninth month.
• MON_10 — name of the tenth month.
• MON_11 — name of the eleventh month.
• MON_12 — name of the twelfth month.
• ABMON_1 — abbreviated name of the first month.
• ABMON_2 — abbreviated name of the second month.
• ABMON_3 — abbreviated name of the third month.
• ABMON_4 — abbreviated name of the fourth month.
• ABMON_5 — abbreviated name of the fifth month.
• ABMON_6 — abbreviated name of the sixth month.
• ABMON_7 — abbreviated name of the seventh month.
• ABMON_8 — abbreviated name of the eighth month.
• ABMON_9 — abbreviated name of the ninth month.
• ABMON_10 — abbreviated name of the tenth month.
• ABMON_11 — abbreviated name of the eleventh month.
• ABMON_12 — abbreviated name of the twelfth month.
• ERA — era description segments.
• ERA_D_FMT — era date format string.
• ERA_D_T_FMT — era date and time format string.
• ERA_T_FMT — era time format string.
• ALT_DIGITS — alternative symbols for digits.

🔢 LC_NUMERIC girlies

• RADIXCHAR (Category: LC_NUMERIC) — radix character.
• THOUSEP (Category: LC_NUMERIC) — separator for thousands.

💬 LC_MESSAGES girlies

• YESEXPR (Category: LC_MESSAGES) — affirmative response expression.
• NOEXPR (Category: LC_MESSAGES) — negative response expression.

💸 LC_MONETARY girlies

• CRNCYSTR (Category: LC_MONETARY) — local currency symbol, and listen closely because this one's a whole situation: it's preceded by - if the symbol should appear before the value, + if the symbol should appear after the value, or . if the symbol should replace the radix character. And if the local currency symbol is the empty string, implementations may return the empty string (""). 🫠

---

⚠️ heads up bestie: if the locale's values for p_cs_precedes and n_cs_precedes do not match, then the value of nl_langinfo(CRNCYSTR) and nl_langinfo_l(CRNCYSTR,loc) is unspecified. Yeah. Undefined. Don't come crying to me 😭

---

The following shall be declared as a function and may also be defined as a macro. A function prototype shall be provided.

char *nl_langinfo(nl_item);
char *nl_langinfo_l(nl_item, locale_t);

Also, inclusion of the <langinfo.h> header may also make visible all symbols from <nl_types.h>. Surprise, she shares 👑

The following sections are informative.

---

🫶 APPLICATION USAGE 🫶

Wherever possible, users are advised to use functions compatible with those in the ISO C standard to access items of langinfo data. Like, pls. Specifically:

• the strftime() function should be used to access date and time information defined in category LC_TIME.
• the localeconv() function should be used to access information corresponding to RADIXCHAR, THOUSEP, and CRNCYSTR.

That's the move. Do that 💅

---

🌸 RATIONALE 🌸

None.

(she said nothing, periodt)

---

🦋 FUTURE DIRECTIONS 🦋

None.

---

💜 SEE ALSO 💜

• Chapter 7, Locale
• <locale.h>
• <nl_types.h>
• The System Interfaces volume of POSIX.1‐2017, nl_langinfo(), localeconv(), strfmon(), strftime()

---

👑 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 .

---

and that's the whole page, bestie 🎀 this little love letter was brought to you by IEEE/The Open Group, 2017, filed under langinfo.h(0P) — go forth and langinfo responsibly 💖✨