devdocs/c/numeric%2Fmath%2Fisinf.html


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    <h1 id="firstHeading" class="firstHeading">isinf</h1>            <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code>&lt;math.h&gt;</code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl t-since-c99"> <td> <pre data-language="c">#define isinf(arg) /* implementation defined */</pre>
</td> <td class="t-dcl-nopad"> </td> <td> <span class="t-mark-rev t-since-c99">(since C99)</span> </td> </tr>  </table> <p>Determines if the given floating-point number <code>arg</code> is positive or negative infinity. The macro returns an integral value.</p>
<p><code><a href="../../types/limits/flt_eval_method" title="c/types/limits/FLT EVAL METHOD">FLT_EVAL_METHOD</a></code> is ignored: even if the argument is evaluated with more range and precision than its type, it is first converted to its semantic type, and the classification is based on that.</p>
<h3 id="Parameters"> Parameters</h3> <table class="t-par-begin"> <tr class="t-par"> <td> arg </td> <td> - </td> <td> floating-point value </td>
</tr>
</table> <h3 id="Return_value"> Return value</h3> <p>Nonzero integral value if <code>arg</code> has an infinite value, <code>0</code> otherwise.</p>
<h3 id="Example"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">#include &lt;stdio.h&gt;
#include &lt;math.h&gt;
#include &lt;float.h&gt;
 
int main(void)
{
    printf("isinf(NAN)         = %d\n", isinf(NAN));
    printf("isinf(INFINITY)    = %d\n", isinf(INFINITY));
    printf("isinf(0.0)         = %d\n", isinf(0.0));
    printf("isinf(DBL_MIN/2.0) = %d\n", isinf(DBL_MIN/2.0));
    printf("isinf(1.0)         = %d\n", isinf(1.0));
    printf("isinf(exp(800))    = %d\n", isinf(exp(800)));
}</pre></div> <p>Possible output:</p>
<div class="text source-text"><pre data-language="c">isinf(NAN)         = 0
isinf(INFINITY)    = 1
isinf(0.0)         = 0
isinf(DBL_MIN/2.0) = 0
isinf(1.0)         = 0
isinf(exp(800))    = 1</pre></div> </div> <h3 id="References"> References</h3>  <ul>
<li> C17 standard (ISO/IEC 9899:2018): </li>
<ul><li> 7.12.3.3 The isinf macro (p: 172) </li></ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.12.3.3 The isinf macro (p: 236) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.12.3.3 The isinf macro (p: 217) </li></ul>
</ul>           <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <div><a href="fpclassify" title="c/numeric/math/fpclassify"> <span class="t-lines"><span>fpclassify</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div> </td> <td> classifies the given floating-point value <br> <span class="t-mark">(function macro)</span>  </td>
</tr> <tr class="t-dsc"> <td> <div><a href="isfinite" title="c/numeric/math/isfinite"> <span class="t-lines"><span>isfinite</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div> </td> <td> checks if the given number has finite value <br> <span class="t-mark">(function macro)</span>  </td>
</tr> <tr class="t-dsc"> <td> <div><a href="isnan" title="c/numeric/math/isnan"> <span class="t-lines"><span>isnan</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div> </td> <td> checks if the given number is NaN <br> <span class="t-mark">(function macro)</span>  </td>
</tr> <tr class="t-dsc"> <td> <div><a href="isnormal" title="c/numeric/math/isnormal"> <span class="t-lines"><span>isnormal</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div> </td> <td> checks if the given number is normal <br> <span class="t-mark">(function macro)</span>  </td>
</tr> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/numeric/math/isinf" title="cpp/numeric/math/isinf">C++ documentation</a></span> for <code>isinf</code> </td>
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