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| <h3 class="section">3.13 <code>tolower</code>—translate characters to lowercase</h3> |
| |
| <p><a name="index-tolower-123"></a><a name="index-g_t_005ftolower-124"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <ctype.h> |
| int tolower(int <var>c</var>); |
| int _tolower(int <var>c</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| <code>tolower</code> is a macro which converts uppercase characters to lowercase, |
| 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 tolower</code>'. |
| |
| <p><code>_tolower</code> performs the same conversion as <code>tolower</code>, but should |
| only be used when <var>c</var> is known to be an uppercase character (<code>A</code>–<code>Z</code>). |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| <code>tolower</code> returns the lowercase 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>_tolower</code> returns the lowercase 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>_tolower</code> is undefined. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| <code>tolower</code> is ANSI C. <code>_tolower</code> is not recommended for portable |
| programs. |
| |
| <p>No supporting OS subroutines are required. |
| |
| <p><br> |
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