devdocs/c/program%2Fsig_err.html


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    <h1 id="firstHeading" class="firstHeading">SIG_ERR</h1>            <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code>&lt;signal.h&gt;</code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl"> <td class="t-dcl-nopad"> <pre data-language="c">#define SIG_ERR /* implementation defined */</pre>
</td> <td class="t-dcl-nopad"> </td> <td class="t-dcl-nopad"> </td> </tr>  </table> <p>A value of type <code>void (*)(int)</code>. When returned by <code><a href="signal" title="c/program/signal">signal</a></code>, indicates that an error has occurred.</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;stdlib.h&gt;
#include &lt;signal.h&gt;
 
void signal_handler(int sig)
{
    printf("Received signal: %d\n", sig);
}
 
int main(void)
{
    /* Install a signal handler. */
    if (signal(SIGTERM, signal_handler) == SIG_ERR)
    {
        printf("Error while installing a signal handler.\n");
        exit(EXIT_FAILURE);
    }
 
    printf("Sending signal: %d\n", SIGTERM);
    if (raise(SIGTERM) != 0)
    {
        printf("Error while raising the SIGTERM signal.\n");
        exit(EXIT_FAILURE);
    }
 
    printf("Exit main()\n");
    return EXIT_SUCCESS;
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">Sending signal: 15
Received signal: 15
Exit main()</pre></div> </div> <h3 id="References"> References</h3>  <ul>
<li> C17 standard (ISO/IEC 9899:2018): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 194) </li></ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 265) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 246) </li></ul>
<li> C89/C90 standard (ISO/IEC 9899:1990): </li>
<ul><li> 4.7 SIGNAL HANDLING &lt;signal.h&gt; </li></ul>
</ul>               <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <div><a href="signal" title="c/program/signal"> <span class="t-lines"><span>signal</span></span></a></div> </td> <td> sets a signal handler for particular signal <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/utility/program/SIG_ERR" title="cpp/utility/program/SIG ERR">C++ documentation</a></span> for <code>SIG_ERR</code> </td>
</tr> </table>           <div class="_attribution">
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