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<title>round</title>
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<basefont size="3"> <a name="round"></a> <a name="tag_03_614"></a><!-- round -->
<!--header start-->
<center><font size="2">The Open Group Base Specifications Issue 6<br>
IEEE Std 1003.1-2001<br>
Copyright &copy; 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
<!--header end-->
<hr size="2" noshade>
<h4><a name="tag_03_614_01"></a>NAME</h4>
<blockquote>round, roundf, roundl - round to the nearest integer value in a floating-point format</blockquote>
<h4><a name="tag_03_614_02"></a>SYNOPSIS</h4>
<blockquote class="synopsis">
<p><code><tt>#include &lt;<a href="../basedefs/math.h.html">math.h</a>&gt;<br>
<br>
double round(double</tt> <i>x</i><tt>);<br>
float roundf(float</tt> <i>x</i><tt>);<br>
long double roundl(long double</tt> <i>x</i><tt>);<br>
</tt></code></p>
</blockquote>
<h4><a name="tag_03_614_03"></a>DESCRIPTION</h4>
<blockquote>
<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
border="0"> The functionality described on this reference page is aligned with the ISO&nbsp;C standard. Any conflict between the
requirements described here and the ISO&nbsp;C standard is unintentional. This volume of IEEE&nbsp;Std&nbsp;1003.1-2001 defers to
the ISO&nbsp;C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
<p>These functions shall round their argument to the nearest integer value in floating-point format, rounding halfway cases away
from zero, regardless of the current rounding direction.</p>
<p>An application wishing to check for error situations should set <i>errno</i> to zero and call
<i>feclearexcept</i>(FE_ALL_EXCEPT) before calling these functions. On return, if <i>errno</i> is non-zero or
<i>fetestexcept</i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.</p>
</blockquote>
<h4><a name="tag_03_614_04"></a>RETURN VALUE</h4>
<blockquote>
<p>Upon successful completion, these functions shall return the rounded integer value.</p>
<p><sup>[<a href="javascript:open_code('MX')">MX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> If
<i>x</i> is NaN, a NaN shall be returned.</p>
<p>If <i>x</i> is &plusmn;0 or &plusmn;Inf, <i>x</i> shall be returned. <img src="../images/opt-end.gif" alt="[Option End]" border=
"0"></p>
<p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
If the correct value would cause overflow, a range error shall occur and <i>round</i>(), <i>roundf</i>(), and <i>roundl</i>() shall
return the value of the macro &plusmn;HUGE_VAL, &plusmn;HUGE_VALF, and &plusmn;HUGE_VALL (with the same sign as <i>x</i>),
respectively. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
</blockquote>
<h4><a name="tag_03_614_05"></a>ERRORS</h4>
<blockquote>
<p>These functions may fail if:</p>
<dl compact>
<dt>Range&nbsp;Error</dt>
<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The result overflows.
<p>If the integer expression (math_errhandling &amp; MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [ERANGE]. If the
integer expression (math_errhandling &amp; MATH_ERREXCEPT) is non-zero, then the overflow floating-point exception shall be raised.
<img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
</dd>
</dl>
</blockquote>
<hr>
<div class="box"><em>The following sections are informative.</em></div>
<h4><a name="tag_03_614_06"></a>EXAMPLES</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_614_07"></a>APPLICATION USAGE</h4>
<blockquote>
<p>On error, the expressions (math_errhandling &amp; MATH_ERRNO) and (math_errhandling &amp; MATH_ERREXCEPT) are independent of
each other, but at least one of them must be non-zero.</p>
</blockquote>
<h4><a name="tag_03_614_08"></a>RATIONALE</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_614_09"></a>FUTURE DIRECTIONS</h4>
<blockquote>
<p>None.</p>
</blockquote>
<h4><a name="tag_03_614_10"></a>SEE ALSO</h4>
<blockquote>
<p><a href="feclearexcept.html"><i>feclearexcept</i>()</a> , <a href="fetestexcept.html"><i>fetestexcept</i>()</a> , the Base
Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href="../basedefs/xbd_chap04.html#tag_04_18">Section 4.18, Treatment of
Error Conditions for Mathematical Functions</a>, <a href="../basedefs/math.h.html"><i>&lt;math.h&gt;</i></a></p>
</blockquote>
<h4><a name="tag_03_614_11"></a>CHANGE HISTORY</h4>
<blockquote>
<p>First released in Issue 6. Derived from the ISO/IEC&nbsp;9899:1999 standard.</p>
</blockquote>
<div class="box"><em>End of informative text.</em></div>
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