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| <!-- %MENU% Character testing and conversion functions --> |
| <h2 class="chapter">4 Character Handling</h2> |
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| <p>Programs that work with characters and strings often need to classify a |
| character—is it alphabetic, is it a digit, is it whitespace, and so |
| on—and perform case conversion operations on characters. The |
| functions in the header file <samp><span class="file">ctype.h</span></samp> are provided for this |
| purpose. |
| <a name="index-ctype_002eh-363"></a> |
| Since the choice of locale and character set can alter the |
| classifications of particular character codes, all of these functions |
| are affected by the current locale. (More precisely, they are affected |
| by the locale currently selected for character classification—the |
| <code>LC_CTYPE</code> category; see <a href="Locale-Categories.html#Locale-Categories">Locale Categories</a>.) |
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| <p>The ISO C<!-- /@w --> standard specifies two different sets of functions. The |
| one set works on <code>char</code> type characters, the other one on |
| <code>wchar_t</code> wide characters (see <a href="Extended-Char-Intro.html#Extended-Char-Intro">Extended Char Intro</a>). |
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| <ul class="menu"> |
| <li><a accesskey="1" href="Classification-of-Characters.html#Classification-of-Characters">Classification of Characters</a>: Testing whether characters are |
| letters, digits, punctuation, etc. |
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| <li><a accesskey="2" href="Case-Conversion.html#Case-Conversion">Case Conversion</a>: Case mapping, and the like. |
| <li><a accesskey="3" href="Classification-of-Wide-Characters.html#Classification-of-Wide-Characters">Classification of Wide Characters</a>: Character class determination for |
| wide characters. |
| <li><a accesskey="4" href="Using-Wide-Char-Classes.html#Using-Wide-Char-Classes">Using Wide Char Classes</a>: Notes on using the wide character |
| classes. |
| <li><a accesskey="5" href="Wide-Character-Case-Conversion.html#Wide-Character-Case-Conversion">Wide Character Case Conversion</a>: Mapping of wide characters. |
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