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<html><!-- #BeginTemplate "/Templates/tmpl.dwt" --><head><!-- #BeginEditable "doctitle" --> <title>PTypes: cset</title><!-- #EndEditable --> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link rel="stylesheet" href="styles.css"></head><body bgcolor="#FFFFFF" leftmargin="40" marginwidth="40"><p><a href="../index.html"><img src="title-1.7.gif" width="213" height="34" alt="C++ Portable Types Library (PTypes) Version 1.7" border="0"></a> <hr noshade><!-- #BeginEditable "body" --> <p class="hpath"><a href="index.html">Top</a>: <a href="basic.html">Basic types</a>: cset</p><ul><li> <h5><a href="cset.constructors.html">Constructors</a></h5></li><li> <h5><a href="cset.operators.html">Operators</a></h5></li><li> <h5><a href="cset.manipulation.html">Manipulation</a></h5></li></ul><p>Character set class (<span class="lang">cset</span>) implements Pascal-style set of integer values from 0 to 255, or set of characters. Unlike Pascal sets, the range of a <span class="lang">cset</span> cannot be changed and is always 0 through 255. <span class="lang">Cset</span> class implements various operators (membership, union, intersection, equality, less than or equal to, etc.) as they are described in the Pascal language. See <a href="cset.operators.html">Operators</a> for details.</p><p><span class="lang">Cset</span> is a packed array of 256 bits, it occupies 32 bytes of static or local memory. Each bit indicates whether the corresponding character is a member of the given set.</p><p>Another difference between <span class="lang">cset</span> and Pascal sets is that since C++ compiler does not have a built-in set constructor like the one in Pascal (e.g. ['A'..'Z', 'a'..'z']), <span class="lang">cset</span> provides a simple run-time interpreter instead (see <a href="cset.constructors.html"> Constructors</a>).</p><p>The <span class="lang">cset</span> class is declared in <span class="lang"><ptypes.h></span>.</p><p>The example below shows the general usage of character sets.</p><blockquote> <pre>cset s = "A-Za-z!"; <span class="comment">// same as ['A'..'Z', 'a'..'z', '!'] in Pascal</span>include(s, '_'); <span class="comment"> // include underscore character</span>include(s, '0', '9'); <span class="comment"> // include all chars from '0' to '9'</span>if ('a' & s) <span class="comment"> // check membership</span> cout << "Letter 'a' found in the set! :)\n";const cset letters = "A-Za-z_"; <span class="comment">// define a set of letters</span>string tok = pin.token(letters); <span class="comment">// read a token from the input stream</span></pre></blockquote><p class="seealso">See also: <a href="cset.constructors.html">Constructors</a>, <a href="cset.operators.html">Operators</a>, <a href="cset.manipulation.html">Manipulation</a></p><!-- #EndEditable --><hr size="1"><a href="../index.html" class="ns">PTypes home</a></body><!-- #EndTemplate --></html>⌨️ 快捷键说明
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