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| <h3 class="section">4.32 <code>getc</code>—read a character (macro)</h3> |
| |
| <p><a name="index-getc-215"></a><a name="index-g_t_005fgetc_005fr-216"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <stdio.h> |
| int getc(FILE *<var>fp</var>); |
| |
| #include <stdio.h> |
| int _getc_r(struct _reent *<var>ptr</var>, FILE *<var>fp</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| <code>getc</code> is a macro, defined in <code>stdio.h</code>. You can use <code>getc</code> |
| to get the next single character from the file or stream |
| identified by <var>fp</var>. As a side effect, <code>getc</code> advances the file's |
| current position indicator. |
| |
| <p>For a subroutine version of this macro, see <code>fgetc</code>. |
| |
| <p>The <code>_getc_r</code> function is simply the reentrant version of <code>getc</code> |
| which passes an additional reentrancy structure pointer argument: <var>ptr</var>. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| The next character (read as an <code>unsigned char</code>, and cast to |
| <code>int</code>), unless there is no more data, or the host system reports a |
| read error; in either of these situations, <code>getc</code> returns <code>EOF</code>. |
| |
| <p>You can distinguish the two situations that cause an <code>EOF</code> result by |
| using the <code>ferror</code> and <code>feof</code> functions. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| ANSI C requires <code>getc</code>; it suggests, but does not require, that |
| <code>getc</code> be implemented as a macro. The standard explicitly permits |
| macro implementations of <code>getc</code> to use the argument more than once; |
| therefore, in a portable program, you should not use an expression |
| with side effects as the <code>getc</code> argument. |
| |
| <p>Supporting OS subroutines required: <code>close</code>, <code>fstat</code>, <code>isatty</code>, |
| <code>lseek</code>, <code>read</code>, <code>sbrk</code>, <code>write</code>. |
| |
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