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<a name="isgreater_002c-isgreaterequal_002c-isless_002c-islessequal_002c-islessgreater_002c-and-isunordered_002d_002d_002dcomparison-macros"></a>
<h3 class="section">1.31 <code>isgreater</code>, <code>isgreaterequal</code>, <code>isless</code>, <code>islessequal</code>, <code>islessgreater</code>, and <code>isunordered</code>&mdash;comparison macros</h3>
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<a name="index-isgreaterequal"></a>
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<a name="index-islessequal"></a>
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<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include &lt;math.h&gt;
int isgreater(real-floating <var>x</var>, real-floating <var>y</var>);
int isgreaterequal(real-floating <var>x</var>, real-floating <var>y</var>);
int isless(real-floating <var>x</var>, real-floating <var>y</var>);
int islessequal(real-floating <var>x</var>, real-floating <var>y</var>);
int islessgreater(real-floating <var>x</var>, real-floating <var>y</var>);
int isunordered(real-floating <var>x</var>, real-floating <var>y</var>);

</pre></div>
<p><strong>Description</strong><br>
<code>isgreater</code>, <code>isgreaterequal</code>, <code>isless</code>, <code>islessequal</code>,
<code>islessgreater</code>, and <code>isunordered</code> are macros defined for use in
comparing floating-point numbers without raising any floating-point
exceptions.
</p>
<p>The relational operators (i.e. &lt;, &gt;, &lt;=, and &gt;=) support the usual mathematical
relationships between numeric values.  For any ordered pair of numeric
values exactly one of the relationships&ndash;less, greater, and equal&ndash;is
true.  Relational operators may raise the &quot;invalid&quot; floating-point
exception when argument values are NaNs.  For a NaN and a numeric value, or
for two NaNs, just the unordered relationship is true (i.e., if one or both
of the arguments a NaN, the relationship is called unordered).  The specified
macros are quiet (non floating-point exception raising) versions of the
relational operators, and other comparison macros that facilitate writing
efficient code that accounts for NaNs without suffering the &quot;invalid&quot;
floating-point exception.  In the synopses shown, &quot;real-floating&quot; indicates
that the argument is an expression of real floating type.
</p>
<p>Please note that saying that the macros do not raise floating-point
exceptions, it is referring to the function that they are performing.  It
is certainly possible to give them an expression which causes an exception.
For example:
</p><dl compact="compact">
<dt><code>NaN &lt; 1.0</code></dt>
<dd><p>causes an &quot;invalid&quot; exception,
</p></dd>
<dt><code>isless(NaN, 1.0)</code></dt>
<dd><p>does not, and
</p></dd>
<dt><code>isless(NaN*0., 1.0)</code></dt>
<dd><p>causes an exception due to the &quot;NaN*0.&quot;, but not from the
resultant reduced comparison of isless(NaN, 1.0).
</p></dd>
</dl>


<br>
<p><strong>Returns</strong><br>
No floating-point exceptions are raised for any of the macros.<br>
The <code>isgreater</code> macro returns the value of (x) &gt; (y).<br>
The <code>isgreaterequal</code> macro returns the value of (x) &gt;= (y).<br>
The <code>isless</code> macro returns the value of (x) &lt; (y).<br>
The <code>islessequal</code> macro returns the value of (x) &lt;= (y).<br>
The <code>islessgreater</code> macro returns the value of (x) &lt; (y) || (x) &gt; (y).<br>
The <code>isunordered</code> macro returns 1 if either of its arguments is NaN and 0 otherwise.
</p>
<br>
<p><strong>Portability</strong><br>
C99, POSIX.
</p>

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