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'\" t
.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH trunc 3 2023-07-20 "Linux man-pages 6.05.01"
.SH NAME
trunc, truncf, truncl \- round to integer, toward zero
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "double trunc(double " x );
.BI "float truncf(float " x );
.BI "long double truncl(long double " x );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR trunc (),
.BR truncf (),
.BR truncl ():
.nf
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
.fi
.SH DESCRIPTION
These functions round
.I x
to the nearest integer value that is not larger in magnitude than
.IR x .
.SH RETURN VALUE
These functions return the rounded integer value, in floating format.
.PP
If
.I x
is integral, infinite, or NaN,
.I x
itself is returned.
.SH ERRORS
No errors occur.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface Attribute Value
T{
.na
.nh
.BR trunc (),
.BR truncf (),
.BR truncl ()
T} Thread safety MT-Safe
.TE
.sp 1
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
glibc 2.1.
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)
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