LRINT(3POSIX)

✨ LRINT(3POSIX) ✨

okay so bestie, welcome to LRINT(3POSIX) from the POSIX Programmer's Manual 💖 this whole page is a glow-up of the standard, and we're gonna read it together like it's a group chat. grab a snack. 🍓

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🫶 PROLOG

okay so first things first, real talk: this manual page is part of the POSIX Programmer's Manual. the Linux implementation of this interface may differ — so if you're on Linux, go consult the corresponding Linux manual page for the deets on Linux behavior. orrr the interface might just not be implemented on Linux at all. 💀 so like. vibe check your platform first, bestie.

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🌸 NAME

lrint, lrintf, lrintl — round to nearest integer value using current rounding direction ✨

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🎀 SYNOPSIS

#include <math.h>

long lrint(double x);
long lrintf(float x);
long lrintl(long double x);

three icons, one job. 💅

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🦋 DESCRIPTION

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 — like, no drama intended, fr fr. This volume of POSIX.1‐2017 defers to the ISO C standard.

These functions shall round their argument to the nearest integer value, rounding according to the current rounding direction. yes, the rounding direction you set. they're not out here making decisions on their own, they're following the vibe you gave them. 👑

An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. so like, clear the deck first, then check the receipts after. 🧾✨

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💖 RETURN VALUE

Upon successful completion, these functions shall return the rounded integer value. slay.

now the messy part, bestie, buckle up:

• If x is NaN, a domain error shall occur and an unspecified value is returned.
• If x is +Inf, a domain error shall occur and an unspecified value is returned.
• If x is -Inf, a domain error shall occur and an unspecified value is returned.
• If the correct value is positive and too large to represent as a long, an unspecified value shall be returned. On systems that support the IEC 60559 Floating-Point option, a domain error shall occur; otherwise, a domain error may occur.
• If the correct value is negative and too large to represent as a long, an unspecified value shall be returned. On systems that support the IEC 60559 Floating-Point option, a domain error shall occur; otherwise, a domain error may occur.

"unspecified value" is the technical way of saying we're not telling you what you get, bestie, and honestly neither is the standard. 🙈 don't build your whole personality on it.

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🔥 ERRORS

These functions shall fail if:

• Domain Error — The x argument is NaN or ±Inf, or the correct value is not representable as an integer.
  • If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM].
  • If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.

These functions may fail if:

• Domain Error — The correct value is not representable as an integer.
  • If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM].
  • If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.

The following sections are informative. 📝 (translation: they're the commentary track, not the binding rules.)

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🌈 EXAMPLES

None. 💀

not a single one. the standard said "figure it out" and honestly? iconic. we love a mysterious queen. 👑

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💜 APPLICATION USAGE

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero. so like, they're not a package deal, but somebody's gotta show up to the party. 🎉

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⭐ RATIONALE

These functions provide floating-to-integer conversions. They round according to the current rounding direction.

If the rounded value is outside the range of the return type, the numeric result is unspecified and the invalid floating-point exception is raised.

When they raise no other floating-point exception and the result differs from the argument, they raise the inexact floating-point exception. like "hey bestie, just so you know, I changed your number a lil bit." 🫶

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🧚 FUTURE DIRECTIONS

None. 🔮

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👑 SEE ALSO

• feclearexcept()
• fetestexcept()
• llrint()
• The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.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 whole page, bestie!! brought to you by IEEE/The Open Group, 2017, page LRINT(3POSIX) — go forth and round responsibly ✨💖🎀