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<html lang="en">
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<title>Character Input - The GNU C Library</title>
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<a name="Character-Input"></a>
Next:&nbsp;<a rel="next" accesskey="n" href="Line-Input.html#Line-Input">Line Input</a>,
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<h3 class="section">12.8 Character Input</h3>

<p><a name="index-reading-from-a-stream_002c-by-characters-977"></a>This section describes functions for performing character-oriented
input.  These narrow streams functions are declared in the header file
<samp><span class="file">stdio.h</span></samp> and the wide character functions are declared in
<samp><span class="file">wchar.h</span></samp>.
<a name="index-stdio_002eh-978"></a><a name="index-wchar_002eh-979"></a>
These functions return an <code>int</code> or <code>wint_t</code> value (for narrow
and wide stream functions respectively) that is either a character of
input, or the special value <code>EOF</code>/<code>WEOF</code> (usually -1).  For
the narrow stream functions it is important to store the result of these
functions in a variable of type <code>int</code> instead of <code>char</code>, even
when you plan to use it only as a character.  Storing <code>EOF</code> in a
<code>char</code> variable truncates its value to the size of a character, so
that it is no longer distinguishable from the valid character
`<samp><span class="samp">(char) -1</span></samp>'.  So always use an <code>int</code> for the result of
<code>getc</code> and friends, and check for <code>EOF</code> after the call; once
you've verified that the result is not <code>EOF</code>, you can be sure that
it will fit in a `<samp><span class="samp">char</span></samp>' variable without loss of information.

<!-- stdio.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: int <b>fgetc</b> (<var>FILE *stream</var>)<var><a name="index-fgetc-980"></a></var><br>
<blockquote><p>This function reads the next character as an <code>unsigned char</code> from
the stream <var>stream</var> and returns its value, converted to an
<code>int</code>.  If an end-of-file condition or read error occurs,
<code>EOF</code> is returned instead.
</p></blockquote></div>

<!-- wchar.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: wint_t <b>fgetwc</b> (<var>FILE *stream</var>)<var><a name="index-fgetwc-981"></a></var><br>
<blockquote><p>This function reads the next wide character from the stream <var>stream</var>
and returns its value.  If an end-of-file condition or read error
occurs, <code>WEOF</code> is returned instead.
</p></blockquote></div>

<!-- stdio.h -->
<!-- POSIX -->
<div class="defun">
&mdash; Function: int <b>fgetc_unlocked</b> (<var>FILE *stream</var>)<var><a name="index-fgetc_005funlocked-982"></a></var><br>
<blockquote><p>The <code>fgetc_unlocked</code> function is equivalent to the <code>fgetc</code>
function except that it does not implicitly lock the stream.
</p></blockquote></div>

<!-- wchar.h -->
<!-- GNU -->
<div class="defun">
&mdash; Function: wint_t <b>fgetwc_unlocked</b> (<var>FILE *stream</var>)<var><a name="index-fgetwc_005funlocked-983"></a></var><br>
<blockquote><p>The <code>fgetwc_unlocked</code> function is equivalent to the <code>fgetwc</code>
function except that it does not implicitly lock the stream.

        <p>This function is a GNU extension.
</p></blockquote></div>

<!-- stdio.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: int <b>getc</b> (<var>FILE *stream</var>)<var><a name="index-getc-984"></a></var><br>
<blockquote><p>This is just like <code>fgetc</code>, except that it is permissible (and
typical) for it to be implemented as a macro that evaluates the
<var>stream</var> argument more than once.  <code>getc</code> is often highly
optimized, so it is usually the best function to use to read a single
character.
</p></blockquote></div>

<!-- wchar.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: wint_t <b>getwc</b> (<var>FILE *stream</var>)<var><a name="index-getwc-985"></a></var><br>
<blockquote><p>This is just like <code>fgetwc</code>, except that it is permissible for it to
be implemented as a macro that evaluates the <var>stream</var> argument more
than once.  <code>getwc</code> can be highly optimized, so it is usually the
best function to use to read a single wide character.
</p></blockquote></div>

<!-- stdio.h -->
<!-- POSIX -->
<div class="defun">
&mdash; Function: int <b>getc_unlocked</b> (<var>FILE *stream</var>)<var><a name="index-getc_005funlocked-986"></a></var><br>
<blockquote><p>The <code>getc_unlocked</code> function is equivalent to the <code>getc</code>
function except that it does not implicitly lock the stream.
</p></blockquote></div>

<!-- wchar.h -->
<!-- GNU -->
<div class="defun">
&mdash; Function: wint_t <b>getwc_unlocked</b> (<var>FILE *stream</var>)<var><a name="index-getwc_005funlocked-987"></a></var><br>
<blockquote><p>The <code>getwc_unlocked</code> function is equivalent to the <code>getwc</code>
function except that it does not implicitly lock the stream.

        <p>This function is a GNU extension.
</p></blockquote></div>

<!-- stdio.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: int <b>getchar</b> (<var>void</var>)<var><a name="index-getchar-988"></a></var><br>
<blockquote><p>The <code>getchar</code> function is equivalent to <code>getc</code> with <code>stdin</code>
as the value of the <var>stream</var> argument.
</p></blockquote></div>

<!-- wchar.h -->
<!-- ISO -->
<div class="defun">
&mdash; Function: wint_t <b>getwchar</b> (<var>void</var>)<var><a name="index-getwchar-989"></a></var><br>
<blockquote><p>The <code>getwchar</code> function is equivalent to <code>getwc</code> with <code>stdin</code>
as the value of the <var>stream</var> argument.
</p></blockquote></div>

<!-- stdio.h -->
<!-- POSIX -->
<div class="defun">
&mdash; Function: int <b>getchar_unlocked</b> (<var>void</var>)<var><a name="index-getchar_005funlocked-990"></a></var><br>
<blockquote><p>The <code>getchar_unlocked</code> function is equivalent to the <code>getchar</code>
function except that it does not implicitly lock the stream.
</p></blockquote></div>

<!-- wchar.h -->
<!-- GNU -->
<div class="defun">
&mdash; Function: wint_t <b>getwchar_unlocked</b> (<var>void</var>)<var><a name="index-getwchar_005funlocked-991"></a></var><br>
<blockquote><p>The <code>getwchar_unlocked</code> function is equivalent to the <code>getwchar</code>
function except that it does not implicitly lock the stream.

        <p>This function is a GNU extension.
</p></blockquote></div>

   <p>Here is an example of a function that does input using <code>fgetc</code>.  It
would work just as well using <code>getc</code> instead, or using
<code>getchar ()</code> instead of <code>fgetc&nbsp;(stdin)</code><!-- /@w -->.  The code would
also work the same for the wide character stream functions.

<pre class="smallexample">     int
     y_or_n_p (const char *question)
     {
       fputs (question, stdout);
       while (1)
         {
           int c, answer;
           /* <span class="roman">Write a space to separate answer from question.</span> */
           fputc (' ', stdout);
           /* <span class="roman">Read the first character of the line.</span>
              <span class="roman">This should be the answer character, but might not be.</span> */
           c = tolower (fgetc (stdin));
           answer = c;
           /* <span class="roman">Discard rest of input line.</span> */
           while (c != '\n' &amp;&amp; c != EOF)
             c = fgetc (stdin);
           /* <span class="roman">Obey the answer if it was valid.</span> */
           if (answer == 'y')
             return 1;
           if (answer == 'n')
             return 0;
           /* <span class="roman">Answer was invalid: ask for valid answer.</span> */
           fputs ("Please answer y or n:", stdout);
         }
     }
</pre>
   <!-- stdio.h -->
<!-- SVID -->
<div class="defun">
&mdash; Function: int <b>getw</b> (<var>FILE *stream</var>)<var><a name="index-getw-992"></a></var><br>
<blockquote><p>This function reads a word (that is, an <code>int</code>) from <var>stream</var>.
It's provided for compatibility with SVID.  We recommend you use
<code>fread</code> instead (see <a href="Block-Input_002fOutput.html#Block-Input_002fOutput">Block Input/Output</a>).  Unlike <code>getc</code>,
any <code>int</code> value could be a valid result.  <code>getw</code> returns
<code>EOF</code> when it encounters end-of-file or an error, but there is no
way to distinguish this from an input word with value -1.
</p></blockquote></div>

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