devdocs/c/numeric%2Ffenv%2Ffeupdateenv.html


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    <h1 id="firstHeading" class="firstHeading">feupdateenv</h1>            <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code>&lt;fenv.h&gt;</code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl t-since-c99"> <td> <pre data-language="c">int feupdateenv( const fenv_t* envp );</pre>
</td> <td class="t-dcl-nopad"> </td> <td> <span class="t-mark-rev t-since-c99">(since C99)</span> </td> </tr>  </table> <p>First, remembers the currently raised floating-point exceptions, then restores the floating-point environment from the object pointed to by <code>envp</code> (similar to <code><a href="feenv" title="c/numeric/fenv/feenv">fesetenv</a></code>), then raises the floating-point exceptions that were saved.</p>
<p>This function may be used to end the non-stop mode established by an earlier call to <code><a href="feholdexcept" title="c/numeric/fenv/feholdexcept">feholdexcept</a></code>.</p>
<h3 id="Parameters"> Parameters</h3> <table class="t-par-begin"> <tr class="t-par"> <td> envp </td> <td> - </td> <td> pointer to the object of type <code>fenv_t</code> set by an earlier call to <code><a href="feholdexcept" title="c/numeric/fenv/feholdexcept">feholdexcept</a></code> or <code>fegetenv</code> or equal to <code><a href="fe_dfl_env" title="c/numeric/fenv/FE DFL ENV">FE_DFL_ENV</a></code> </td>
</tr>
</table> <h3 id="Return_value"> Return value</h3> <p><code>0</code> on success, non-zero 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;fenv.h&gt;
#include &lt;float.h&gt;
 
#pragma STDC FENV_ACCESS ON
 
void show_fe_exceptions(void)
{
    printf("current exceptions raised: ");
    if(fetestexcept(FE_DIVBYZERO))     printf(" FE_DIVBYZERO");
    if(fetestexcept(FE_INEXACT))       printf(" FE_INEXACT");
    if(fetestexcept(FE_INVALID))       printf(" FE_INVALID");
    if(fetestexcept(FE_OVERFLOW))      printf(" FE_OVERFLOW");
    if(fetestexcept(FE_UNDERFLOW))     printf(" FE_UNDERFLOW");
    if(fetestexcept(FE_ALL_EXCEPT)==0) printf(" none");
    printf("\n");
}
 
double x2 (double x)   /* times two */
{
    fenv_t curr_excepts;
 
    /* Save and clear current f-p environment. */
    feholdexcept(&amp;curr_excepts);
 
    /* Raise inexact and overflow exceptions. */
    printf("In x2():  x = %f\n", x=x*2.0);
    show_fe_exceptions();
    feclearexcept(FE_INEXACT);   /* hide inexact exception from caller */
 
    /* Merge caller's exceptions (FE_INVALID)        */
    /* with remaining x2's exceptions (FE_OVERFLOW). */
    feupdateenv(&amp;curr_excepts);
    return x;
}
 
int main(void)
{    
    feclearexcept(FE_ALL_EXCEPT);
    feraiseexcept(FE_INVALID);   /* some computation with invalid argument */
    show_fe_exceptions();
    printf("x2(DBL_MAX) = %f\n", x2(DBL_MAX));
    show_fe_exceptions();
 
    return 0;
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">current exceptions raised:  FE_INVALID
In x2():  x = inf
current exceptions raised:  FE_INEXACT FE_OVERFLOW
x2(DBL_MAX) = inf
current exceptions raised:  FE_INVALID FE_OVERFLOW</pre></div> </div> <h3 id="References"> References</h3>  <ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.6.4.4 The feupdateenv function (p: 214-215) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.6.4.4 The feupdateenv function (p: 195-196) </li></ul>
</ul>      <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <div><a href="feholdexcept" title="c/numeric/fenv/feholdexcept"> <span class="t-lines"><span>feholdexcept</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> saves the environment, clears all status flags and ignores all future errors <br> <span class="t-mark">(function)</span>  </td>
</tr> <tr class="t-dsc"> <td> <div><a href="feenv" title="c/numeric/fenv/feenv"> <span class="t-lines"><span>fegetenv</span><span>fesetenv</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> saves or restores the current floating-point environment <br> <span class="t-mark">(function)</span>  </td>
</tr> <tr class="t-dsc"> <td> <div><a href="fe_dfl_env" title="c/numeric/fenv/FE DFL ENV"> <span class="t-lines"><span>FE_DFL_ENV</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> default floating-point environment <br> <span class="t-mark">(macro constant)</span>  </td>
</tr> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/numeric/fenv/feupdateenv" title="cpp/numeric/fenv/feupdateenv">C++ documentation</a></span> for <code>feupdateenv</code> </td>
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