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| <h3 class="section">4.30 <code>fwide</code>—set and determine the orientation of a FILE stream</h3> |
| |
| <p><a name="index-fwide-211"></a><a name="index-g_t_005ffwide_005fr-212"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <wchar.h> |
| int fwide(FILE *<var>fp</var>, int <var>mode</var>) |
| |
| int _fwide_r(struct _reent *<var>ptr</var>, FILE *<var>fp</var>, int <var>mode</var>) |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| When <var>mode</var> is zero, the <code>fwide</code> function determines the current |
| orientation of <var>fp</var>. It returns a value > 0 if <var>fp</var> is |
| wide-character oriented, i.e. if wide character I/O is permitted but |
| char I/O is disallowed. It returns a value < 0 if <var>fp</var> is byte |
| oriented, i.e. if char I/O is permitted but wide character I/O is |
| disallowed. It returns zero if <var>fp</var> has no orientation yet; in |
| this case the next I/O operation might change the orientation (to byte |
| oriented if it is a char I/O operation, or to wide-character oriented |
| if it is a wide character I/O operation). |
| |
| <p>Once a stream has an orientation, it cannot be changed and persists |
| until the stream is closed, unless the stream is re-opened with freopen, |
| which removes the orientation of the stream. |
| |
| <p>When <var>mode</var> is non-zero, the <code>fwide</code> function first attempts to set |
| <var>fp</var>'s orientation (to wide-character oriented if <var>mode</var> > 0, or to |
| byte oriented if <var>mode</var> < 0). It then returns a value denoting the |
| current orientation, as above. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| The <code>fwide</code> function returns <var>fp</var>'s orientation, after possibly |
| changing it. A return value > 0 means wide-character oriented. A return |
| value < 0 means byte oriented. A return value of zero means undecided. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| C99, POSIX.1-2001. |
| |
| <p><br> |
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