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| <h3 class="section">7.8 Yes-or-No Questions</h3> |
| |
| <p>Some non GUI programs ask a yes-or-no question. If the messages |
| (especially the questions) are translated into foreign languages, be |
| sure that you localize the answers too. It would be very bad habit to |
| ask a question in one language and request the answer in another, often |
| English. |
| |
| <p>The GNU C library contains <code>rpmatch</code> to give applications easy |
| access to the corresponding locale definitions. |
| |
| <!-- GNU --> |
| <!-- stdlib.h --> |
| <div class="defun"> |
| — Function: int <b>rpmatch</b> (<var>const char *response</var>)<var><a name="index-rpmatch-799"></a></var><br> |
| <blockquote><p>The function <code>rpmatch</code> checks the string in <var>response</var> whether |
| or not it is a correct yes-or-no answer and if yes, which one. The |
| check uses the <code>YESEXPR</code> and <code>NOEXPR</code> data in the |
| <code>LC_MESSAGES</code> category of the currently selected locale. The |
| return value is as follows: |
| |
| <dl> |
| <dt><code>1</code><dd>The user entered an affirmative answer. |
| |
| <br><dt><code>0</code><dd>The user entered a negative answer. |
| |
| <br><dt><code>-1</code><dd>The answer matched neither the <code>YESEXPR</code> nor the <code>NOEXPR</code> |
| regular expression. |
| </dl> |
| |
| <p>This function is not standardized but available beside in GNU libc at |
| least also in the IBM AIX library. |
| </p></blockquote></div> |
| |
| <p class="noindent">This function would normally be used like this: |
| |
| <pre class="smallexample"> ... |
| /* <span class="roman">Use a safe default.</span> */ |
| _Bool doit = false; |
| |
| fputs (gettext ("Do you really want to do this? "), stdout); |
| fflush (stdout); |
| /* <span class="roman">Prepare the </span><code>getline</code><span class="roman"> call.</span> */ |
| line = NULL; |
| len = 0; |
| while (getline (&line, &len, stdin) >= 0) |
| { |
| /* <span class="roman">Check the response.</span> */ |
| int res = rpmatch (line); |
| if (res >= 0) |
| { |
| /* <span class="roman">We got a definitive answer.</span> */ |
| if (res > 0) |
| doit = true; |
| break; |
| } |
| } |
| /* <span class="roman">Free what </span><code>getline</code><span class="roman"> allocated.</span> */ |
| free (line); |
| </pre> |
| <p>Note that the loop continues until an read error is detected or until a |
| definitive (positive or negative) answer is read. |
| |
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