diff options
Diffstat (limited to 'devdocs/c/language%2F_noreturn.html')
| -rw-r--r-- | devdocs/c/language%2F_noreturn.html | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/devdocs/c/language%2F_noreturn.html b/devdocs/c/language%2F_noreturn.html new file mode 100644 index 00000000..ff87fe14 --- /dev/null +++ b/devdocs/c/language%2F_noreturn.html @@ -0,0 +1,61 @@ + <h1 id="firstHeading" class="firstHeading">_Noreturn function specifier</h1> <p>Specifies that the function does not return to its point of invocation.</p> +<h3 id="Syntax"> Syntax</h3> <table class="t-sdsc-begin"> <tr class="t-sdsc"> <td> <code>_Noreturn</code> <span class="t-spar">function_declaration</span> </td> <td class="t-sdsc-nopad"> </td> <td> <span class="t-mark-rev t-since-c11">(since C11)</span><span class="t-mark-rev t-deprecated-c23">(deprecated in C23)</span> </td> +</tr> +</table> <h3 id="Explanation"> Explanation</h3> <p>The <code>_Noreturn</code> keyword appears in a function declaration and specifies that the function does not return by executing the return statement or by reaching the end of the function body (it may return by executing <code><a href="../program/longjmp" title="c/program/longjmp">longjmp</a></code>). If the function declared <code>_Noreturn</code> returns, the behavior is undefined. A compiler diagnostic is recommended if this can be detected.</p> +<p>The <code>_Noreturn</code> specifier may appear more than once in the same function declaration, the behavior is the same as if it appeared once.</p> +<p>This specifier is typically used through the convenience macro <a href="../types" title="c/types"><code>noreturn</code></a>, which is provided in the header <code><stdnoreturn.h></code>.</p> +<table class="t-rev-begin"> <tr class="t-rev t-since-c23"> +<td> <p><code>_Noreturn</code> function specifier is deprecated. <code>[[<a href="attributes/noreturn" title="c/language/attributes/noreturn">noreturn</a>]]</code> attribute should be used instead.</p> +<p>The macro <code>noreturn</code> is also deprecated.</p> +</td> <td><span class="t-mark-rev t-since-c23">(since C23)</span></td> +</tr> </table> <h3 id="Keywords"> Keywords</h3> <p><a href="../keyword/_noreturn" title="c/keyword/ Noreturn"><code>_Noreturn</code></a></p> +<h3 id="Standard_library"> Standard library</h3> <p>The following functions are <code>noreturn</code> in the standard library:</p> +<ul> +<li> <code><a href="../program/abort" title="c/program/abort">abort()</a></code> </li> +<li> <code><a href="../program/exit" title="c/program/exit">exit()</a></code> </li> +<li> <code><a href="../program/_exit" title="c/program/ Exit">_Exit()</a></code> </li> +<li> <code><a href="../program/quick_exit" title="c/program/quick exit">quick_exit()</a></code> </li> +<li> <code><a href="../thread/thrd_exit" title="c/thread/thrd exit">thrd_exit()</a></code> </li> +<li> <code><a href="../program/longjmp" title="c/program/longjmp">longjmp()</a></code> </li> +</ul> <h3 id="Example"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">#include <stdio.h> +#include <stdlib.h> +#include <stdnoreturn.h> + +// causes undefined behavior if i <= 0 +// exits if i > 0 +noreturn void exit_now(int i) // or _Noreturn void exit_now(int i) +{ + if (i > 0) + exit(i); +} + +int main(void) +{ + puts("Preparing to exit..."); + exit_now(2); + puts("This code is never executed."); +}</pre></div> <p>Output:</p> +<div class="text source-text"><pre data-language="c">Preparing to exit...</pre></div> </div> <h3 id="References"> References</h3> <ul> +<li> C23 standard (ISO/IEC 9899:2023): </li> +<ul> +<li> 6.7.4 Function specifiers (p: TBD) </li> +<li> 7.23 _Noreturn <stdnoreturn.h> (p: TBD) </li> +</ul> +<li> C17 standard (ISO/IEC 9899:2018): </li> +<ul> +<li> 6.7.4 Function specifiers (p: 90-91) </li> +<li> 7.23 _Noreturn <stdnoreturn.h> (p: 263) </li> +</ul> +<li> C11 standard (ISO/IEC 9899:2011): </li> +<ul> +<li> 6.7.4 Function specifiers (p: 125-127) </li> +<li> 7.23 _Noreturn <stdnoreturn.h> (p: 361) </li> +</ul> +</ul> <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <code>[[<a href="attributes/noreturn" title="c/language/attributes/noreturn">noreturn</a>]]</code><span class="t-mark-rev t-since-c23">(C23)</span><br><code>[[<a href="attributes/noreturn" title="c/language/attributes/noreturn">_Noreturn</a>]]</code><span class="t-mark-rev t-since-c23">(C23)</span><span class="t-mark">(deprecated)</span> </td> <td> indicates that the function does not return<br><span class="t-mark">(attribute specifier)</span> </td> +</tr> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/language/attributes/noreturn" title="cpp/language/attributes/noreturn">C++ documentation</a></span> for <code>[[noreturn]]</code> </td> +</tr> </table> <div class="_attribution"> + <p class="_attribution-p"> + © cppreference.com<br>Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.<br> + <a href="https://en.cppreference.com/w/c/language/_Noreturn" class="_attribution-link">https://en.cppreference.com/w/c/language/_Noreturn</a> + </p> +</div> |