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+    <h1 id="firstHeading" class="firstHeading">FE_DFL_ENV</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">#define FE_DFL_ENV  /*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>The macro constant <code>FE_DFL_ENV</code> expands to an expression of type <code>const fenv_t*</code>, which points to a full copy of the default floating-point environment, that is, the environment as loaded at program startup.</p>
+<p>Additional macros that begin with <code>FE_</code> followed by uppercase letters, and have the type <code>const fenv_t*</code>, may be supported by an implementation.</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;
+ 
+#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");
+}
+ 
+void show_fe_rounding_method(void)
+{
+    printf("current rounding method:    ");
+    switch (fegetround()) {
+           case FE_TONEAREST:  printf ("FE_TONEAREST");  break;
+           case FE_DOWNWARD:   printf ("FE_DOWNWARD");   break;
+           case FE_UPWARD:     printf ("FE_UPWARD");     break;
+           case FE_TOWARDZERO: printf ("FE_TOWARDZERO"); break;
+           default:            printf ("unknown");
+    };
+    printf("\n");
+}
+ 
+void show_fe_environment(void)
+{
+    show_fe_exceptions();
+    show_fe_rounding_method();
+} 
+ 
+int main()
+{
+    printf("On startup:\n");
+    show_fe_environment();
+ 
+    // Change environment
+    fesetround(FE_DOWNWARD);     // change rounding mode
+    feraiseexcept(FE_INVALID);   // raise exception
+    printf("\nBefore restoration:\n");
+    show_fe_environment();
+ 
+    fesetenv(FE_DFL_ENV);    // restore
+    printf("\nAfter restoring default environment:\n");
+    show_fe_environment();
+}</pre></div> <p>Output:</p>
+<div class="text source-text"><pre data-language="c">On startup:
+current exceptions raised:  none
+current rounding method:    FE_TONEAREST
+ 
+Before restoration:
+current exceptions raised:  FE_INVALID
+current rounding method:    FE_DOWNWARD
+ 
+After restoring default environment:
+current exceptions raised:  none
+current rounding method:    FE_TONEAREST</pre></div> </div> <h3 id="References"> References</h3>  <ul>
+<li> C11 standard (ISO/IEC 9899:2011): </li>
+<ul><li> 7.6/9 Floating-point environment &lt;fenv.h&gt; (p: 208) </li></ul>
+<li> C99 standard (ISO/IEC 9899:1999): </li>
+<ul><li> 7.6/8 Floating-point environment &lt;fenv.h&gt; (p: 188-189) </li></ul>
+</ul>      <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <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="feupdateenv" title="c/numeric/fenv/feupdateenv"> <span class="t-lines"><span>feupdateenv</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> restores the floating-point environment and raises the previously raise exceptions <br> <span class="t-mark">(function)</span>  </td>
+</tr> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/numeric/fenv/FE_DFL_ENV" title="cpp/numeric/fenv/FE DFL ENV">C++ documentation</a></span> for <code>FE_DFL_ENV</code> </td>
+</tr> </table>           <div class="_attribution">
+  <p class="_attribution-p">
+    &copy; cppreference.com<br>Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.<br>
+    <a href="https://en.cppreference.com/w/c/numeric/fenv/FE_DFL_ENV" class="_attribution-link">https://en.cppreference.com/w/c/numeric/fenv/FE_DFL_ENV</a>
+  </p>
+</div>