man3/trunc.3

   1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .TH TRUNC 3 2021-03-22 "Linux man-pages (unreleased)"
   6 .SH NAME
   7 trunc, truncf, truncl \- round to integer, toward zero
   8 .SH LIBRARY
   9 Math library
  10 .RI ( libm ", " \-lm )
  11 .SH SYNOPSIS
  12 .nf
  13 .B #include <math.h>
  14 .PP
  15 .BI "double trunc(double " x );
  16 .BI "float truncf(float " x );
  17 .BI "long double truncl(long double " x );
  18 .fi
  19 .PP
  20 .RS -4
  21 Feature Test Macro Requirements for glibc (see
  22 .BR feature_test_macros (7)):
  23 .RE
  24 .PP
  25 .BR trunc (),
  26 .BR truncf (),
  27 .BR truncl ():
  28 .nf
  29     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  30 .fi
  31 .SH DESCRIPTION
  32 These functions round
  33 .I x
  34 to the nearest integer value that is not larger in magnitude than
  35 .IR x .
  36 .SH RETURN VALUE
  37 These functions return the rounded integer value, in floating format.
  38 .PP
  39 If
  40 .I x
  41 is integral, infinite, or NaN,
  42 .I x
  43 itself is returned.
  44 .SH ERRORS
  45 No errors occur.
  46 .SH VERSIONS
  47 These functions first appeared in glibc in version 2.1.
  48 .SH ATTRIBUTES
  49 For an explanation of the terms used in this section, see
  50 .BR attributes (7).
  51 .ad l
  52 .nh
  53 .TS
  54 allbox;
  55 lbx lb lb
  56 l l l.
  57 Interface       Attribute       Value
  58 T{
  59 .BR trunc (),
  60 .BR truncf (),
  61 .BR truncl ()
  62 T}      Thread safety   MT-Safe
  63 .TE
  64 .hy
  65 .ad
  66 .sp 1
  67 .SH STANDARDS
  68 C99, POSIX.1-2001, POSIX.1-2008.
  69 .SH NOTES
  70 The integral value returned by these functions may be too large
  71 to store in an integer type
  72 .RI ( int ,
  73 .IR long ,
  74 etc.).
  75 To avoid an overflow, which will produce undefined results,
  76 an application should perform a range check on the returned value
  77 before assigning it to an integer type.
  78 .SH SEE ALSO
  79 .BR ceil (3),
  80 .BR floor (3),
  81 .BR lrint (3),
  82 .BR nearbyint (3),
  83 .BR rint (3),
  84 .BR round (3)