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<h3 class="section">3.14 <code>toupper</code>&mdash;translate characters to uppercase</h3>
<p><a name="index-toupper-125"></a><a name="index-g_t_005ftoupper-126"></a><strong>Synopsis</strong>
<pre class="example"> #include &lt;ctype.h&gt;
int toupper(int <var>c</var>);
int _toupper(int <var>c</var>);
</pre>
<p><strong>Description</strong><br>
<code>toupper</code> is a macro which converts lowercase characters to uppercase,
leaving all other characters unchanged. It is only defined when
<var>c</var> is an integer in the range <code>EOF</code> to <code>255</code>.
<p>You can use a compiled subroutine instead of the macro definition by
undefining this macro using `<code>#undef toupper</code>'.
<p><code>_toupper</code> performs the same conversion as <code>toupper</code>, but should
only be used when <var>c</var> is known to be a lowercase character (<code>a</code>&ndash;<code>z</code>).
<p><br>
<strong>Returns</strong><br>
<code>toupper</code> returns the uppercase equivalent of <var>c</var> when it is a
character between <code>a</code> and <code>z</code>, and <var>c</var> otherwise.
<p><code>_toupper</code> returns the uppercase equivalent of <var>c</var> when it is a
character between <code>a</code> and <code>z</code>. If <var>c</var> is not one of these
characters, the behaviour of <code>_toupper</code> is undefined.
<p><br>
<strong>Portability</strong><br>
<code>toupper</code> is ANSI C. <code>_toupper</code> is not recommended for portable programs.
<p>No supporting OS subroutines are required.
<p><br>
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