carta
floorf(3)

floorf3

Largest integral value not greater than argument

Part of floor(3).

Usage

double floor(double x); float floorf(float x); long double floorl(long double x);

_ISOC99_SOURCE { | | _POSIX_C_SOURCE >= 200112L}

Library

Math library (libm, -lm)

Overview

These functions return the largest integral value that is not greater than x.

For example, floor(0.5) is 0.0, and floor(-0.5) is -1.0.

Return value

These functions return the floor of x.

If x is integral, +0, -0, NaN, or an infinity, x itself is returned.

Errors

No errors occur.

Attributes

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
floor(), floorf(), floorl()Thread safetyMT-Safe

History

  • Arch Linux 2026-11-01: the text shown here
  • Debian 13 (Trixie)
  • Debian 12 (Bookworm)
  • Debian 11 (Bullseye)
  • Debian 10 (Buster)
  • Debian 9 (Stretch)
  • Debian 8 (Jessie)
  • Debian 7 (Wheezy)
  • Debian 6.0 (Squeeze)
  • Debian 5.0 (Lenny)
  • Debian 4.0 (Etch)
  • Debian 3.1 (Sarge)
  • Debian 3.0 (Woody)

Standards

C11, POSIX.1-2008.

History

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

SUSv2 and POSIX.1-2001 contain text about overflow (which might set errno to ERANGE, or raise an FE_OVERFLOW exception). In practice, the result cannot overflow on any current machine, so this error-handling stuff was just nonsense. (More precisely, overflow can happen only when the maximum value of the exponent is smaller than the number of mantissa bits. For the IEEE-754 standard 32-bit and 64-bit floating-point numbers the maximum value of the exponent is 127 (respectively, 1023), and the number of mantissa bits including the implicit bit is 24 (respectively, 53).) This was removed in POSIX.1-2008.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.