.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
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.TH TRUNC 3  2013-06-21 "" "Linux Programmer's Manual"
.SH NAME
trunc, truncf, truncl \- round to integer, toward zero
.SH SYNOPSIS
.nf
.B #include <math.h>
.sp
.BI "double trunc(double " x );
.br
.BI "float truncf(float " x );
.br
.BI "long double truncl(long double " x );
.fi
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR trunc (),
.BR truncf (),
.BR truncl ():
.RS 4
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.SH DESCRIPTION
These functions round
.I x
to the nearest integer
not larger in absolute value.
.SH RETURN VALUE
These functions return the rounded integer value.

If
.IR x
is integral, infinite, or NaN,
.I x
itself is returned.
.SH ERRORS
No errors occur.
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
.SS Multithreading (see pthreads(7))
The
.BR trunc (),
.BR truncf (),
and
.BR truncl ()
functions are thread-safe.
.SH CONFORMING TO
C99, POSIX.1-2001.
.SH NOTES
The integral value returned by these functions may be too large
to store in an integer type
.RI ( int ,
.IR 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.
.SH SEE ALSO
.BR ceil (3),
.BR floor (3),
.BR lrint (3),
.BR nearbyint (3),
.BR rint (3),
.BR round (3)
.SH COLOPHON
This page is part of release 3.74 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%http://www.kernel.org/doc/man\-pages/.