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<title>PTypes: streams: examples</title>
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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="streams.html">Streams</a>:
Examples </p>
<p><b>Example 1.</b> This simple program creates a new file and writes a string
to it.</p>
<blockquote>
<pre>#include <pstreams.h>
USING_PTYPES
int main()
{
<span class="comment">// the outfile object is declared and constructed outside
// the try...catch clause, since the exception object
// contains a reference to the stream that caused the error.
// besides, stream constructors and destructors in PTypes
// never throw exceptions.</span>
outfile f(fname);
f.set_bufsize(1024); <span class="comment">// the default value in this version is 8192</span>
try
{
f.open();
f.put("This is a test file.");
f.close();
}
catch (estream* e)
{
perr.putf("File error: %s\n", e->get_message());
delete e;
}
return 0;
}
</pre>
</blockquote>
<p><b>Example 2.</b> This program reads a C source, extracts identifiers and builds
a usage dictionary. It does not understand C comments and string literals though,
but can be easily improved to understand them too.</p>
<blockquote>
<pre>#include <ptypes.h>
#include <pstreams.h>
USING_PTYPES
const cset letters("_A-Za-z");
const cset digits("0-9");
const cset identchars = letters + digits;
const cset otherchars = !letters;
void main(int argc, char* argv[])
{
tstrlist<void*> dic(SL_SORTED | SL_CASESENS);
infile f(argv[1]);
try
{
f.open();
while (!f.get_eof())
{
char c = f.preview();
<span class="comment">// a C identifier begins with a letter</span>
if (c & letters)
{
<span class="comment">// ... and may contain letters and digits</span>
string ident = f.token(identchars);
int i;
if (!dic.search(ident, i))
dic.ins(i, ident, 0);
}
else
<span class="comment">// ignore everything else</span>
f.skiptoken(otherchars);
}
}
catch (estream* e)
{
pout.putf("Error: %s\n", e->get_message());
delete e;
}
<span class="comment">// now print the dictionary</span>
for (int i = 0; i < dic.get_count(); i++)
pout.putline(dic.getkey(i));
}
</pre>
</blockquote>
<p class="seealso">See also: <a href="streams.iobase.html">iobase</a>, <a href="streams.instm.html">instm</a>,
<a href="streams.infile.html">infile</a>, <a href="streams.outstm.html">outstm</a>,
<a href="streams.outfile.html">outfile</a>, <a href="streams.errors.html">Error
handling</a></p>
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