1TRUNC(3P)                  POSIX Programmer's Manual                 TRUNC(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       trunc, truncf, truncl — round to truncated integer value
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SYNOPSIS

16       #include <math.h>
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18       double trunc(double x);
19       float truncf(float x);
20       long double truncl(long double x);
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DESCRIPTION

23       The functionality described on this reference page is aligned with  the
24       ISO C  standard.  Any  conflict between the requirements described here
25       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
26       defers to the ISO C standard.
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28       These  functions  shall  round  their argument to the integer value, in
29       floating format, nearest to but no larger in magnitude than  the  argu‐
30       ment.
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RETURN VALUE

33       Upon  successful completion, these functions shall return the truncated
34       integer value.
35       The result shall have the same sign as x.
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37       If x is NaN, a NaN shall be returned.
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39       If x is ±0 or ±Inf, x shall be returned.
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ERRORS

42       No errors are defined.
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44       The following sections are informative.
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EXAMPLES

47       None.
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APPLICATION USAGE

50       The integral value returned by these functions need not be  expressible
51       as  an intmax_t.  The return value should be tested before assigning it
52       to an integer type to avoid the undefined results of an  integer  over‐
53       flow.
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55       These  functions  may raise the inexact floating-point exception if the
56       result differs in value from the argument.
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RATIONALE

59       None.
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FUTURE DIRECTIONS

62       None.
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SEE ALSO

65       The Base Definitions volume of POSIX.1‐2008, <math.h>
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68       Portions of this text are reprinted and reproduced in  electronic  form
69       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
70       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
71       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
72       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
73       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
74       event of any discrepancy between this version and the original IEEE and
75       The  Open Group Standard, the original IEEE and The Open Group Standard
76       is the referee document. The original Standard can be  obtained  online
77       at http://www.unix.org/online.html .
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79       Any  typographical  or  formatting  errors that appear in this page are
80       most likely to have been introduced during the conversion of the source
81       files  to  man page format. To report such errors, see https://www.ker‐
82       nel.org/doc/man-pages/reporting_bugs.html .
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86IEEE/The Open Group                  2013                            TRUNC(3P)
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