man3/trunc.3

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  25 .TH TRUNC 3  2017-09-15 "" "Linux Programmer's Manual"
  26 .SH NAME
  27 trunc, truncf, truncl \- round to integer, toward zero
  28 .SH SYNOPSIS
  29 .nf
  30 .B #include <math.h>
  31 .PP
  32 .BI "double trunc(double " x );
  33 .BI "float truncf(float " x );
  34 .BI "long double truncl(long double " x );
  35 .fi
  36 .PP
  37 Link with \fI\-lm\fP.
  38 .PP
  39 .in -4n
  40 Feature Test Macro Requirements for glibc (see
  41 .BR feature_test_macros (7)):
  42 .in
  43 .PP
  44 .ad l
  45 .BR trunc (),
  46 .BR truncf (),
  47 .BR truncl ():
  48 .RS 4
  49 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  50 .RE
  51 .ad
  52 .SH DESCRIPTION
  53 These functions round
  54 .I x
  55 to the nearest integer value that is not larger in magnitude than
  56 .IR x .
  57 .SH RETURN VALUE
  58 These functions return the rounded integer value, in floating format.
  59 .PP
  60 If
  61 .IR x
  62 is integral, infinite, or NaN,
  63 .I x
  64 itself is returned.
  65 .SH ERRORS
  66 No errors occur.
  67 .SH VERSIONS
  68 These functions first appeared in glibc in version 2.1.
  69 .SH ATTRIBUTES
  70 For an explanation of the terms used in this section, see
  71 .BR attributes (7).
  72 .TS
  73 allbox;
  74 lbw27 lb lb
  75 l l l.
  76 Interface       Attribute       Value
  77 T{
  78 .BR trunc (),
  79 .BR truncf (),
  80 .BR truncl ()
  81 T}      Thread safety   MT-Safe
  82 .TE
  83 .SH CONFORMING TO
  84 C99, POSIX.1-2001, POSIX.1-2008.
  85 .SH NOTES
  86 The integral value returned by these functions may be too large
  87 to store in an integer type
  88 .RI ( int ,
  89 .IR long ,
  90 etc.).
  91 To avoid an overflow, which will produce undefined results,
  92 an application should perform a range check on the returned value
  93 before assigning it to an integer type.
  94 .SH SEE ALSO
  95 .BR ceil (3),
  96 .BR floor (3),
  97 .BR lrint (3),
  98 .BR nearbyint (3),
  99 .BR rint (3),
 100 .BR round (3)