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<p><a href="../index.html"><img src="title-21.png" width="253" height="39" alt="C++ Portable Types Library (PTypes) Version 2.1" border="0"></a>
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<p class="hpath"><a href="index.html">Top</a>: <a href="basic.html">Basic types</a>:
cset</p>
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<h5><a href="cset.constructors.html">Constructors</a></h5>
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<h5><a href="cset.operators.html">Operators</a></h5>
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<h5><a href="cset.manipulation.html">Manipulation</a></h5>
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<p>The 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 a 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 <a href="include/ptypes.h.html"><ptypes.h></a>.</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>
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