truncf(3)

truncf3

Round to integer, toward zero

Part of trunc(3).

Usage

#include <math.h>

double trunc(double x); float truncf(float x); long double truncl(long double x);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

trunc(), truncf(), truncl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

Library

Math library (libm, -lm)

Overview

These functions round x to the nearest integer value that is not larger in magnitude than x.

Return value

These functions return the rounded integer value, in floating format.

If x is integral, infinite, or NaN, x itself is returned.

Errors

No errors occur.

Attributes

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

InterfaceAttributeValue
trunc(), truncf(), truncl()Thread safetyMT-Safe

Notes

The integral value returned by these functions may be too large to store in an integer type (int, long, etc.). To avoid an overflow, which will produce undefined results, an application should perform a range check on the returned value before assigning it to an integer type.

Releases

13 releases since Debian 3.0 (Woody); the text changed 12 times.

  1. 3.0
  2. 3.1
  3. 4.0
  4. 5.0
  5. 6.0
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. 13
  13. Arch

Standards

C11, POSIX.1-2008.

History

glibc 2.1. C99, POSIX.1-2001.

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