Update of /cvsroot/boost/boost/libs/conversion
In directory sc8-pr-cvs3.sourceforge.net:/tmp/cvs-serv22202/libs/conversion
Modified Files:
lexical_cast.htm
Log Message:
added: FAQ and References section, updated: Changes
Index: lexical_cast.htm
===================================================================
RCS file: /cvsroot/boost/boost/libs/conversion/lexical_cast.htm,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -d -r1.11 -r1.12
--- lexical_cast.htm 16 Jan 2007 22:22:19 -0000 1.11
+++ lexical_cast.htm 20 May 2007 16:25:34 -0000 1.12
@@ -21,6 +21,10 @@
<li>
<a
href="#bad_lexical_cast"><code>bad_lexical_cast</code></a></li>
<li>
+ <a href="#faq">Frequently Asked
Questions</a></li>
+ <li>
+ <a href="#references">References</a></li>
+ <li>
<a href="#changes">Changes</a></li>
</ul>
<hr>
@@ -192,7 +196,39 @@
failure.
<hr>
+<h2><a name="faq">Frequently Asked Questions</h2>
+ <p> Q: Why does <code>lexical_cast<int8_t>("127")</code> throw
<code>bad_lexical_cast</code>?
+ <br> A: The type <code>int8_t</code> is a typedef to <code>char</code> or
<code>signed char</code>.
+ Lexical conversion to these types is simply reading a byte from source but
since the source has
+ more than one byte, the exception is thrown.
+ <p>Please use other integer types such as <code>int</code> or <code>short
int</code>. If bounds checking
+ is important, you can also call <a
href="../../libs/numeric/conversion/doc/numeric_cast.html">numeric_cast</a>:
+
+<pre><a
href="../../libs/numeric/conversion/doc/numeric_cast.html">numeric_cast</a><int8_t>(lexical_cast<int>("127"));</pre>
+
+ <p> Q: What does <code>lexical_cast<std::string></code> of an
<code>int8_t</code> or <code>uint8_t</code> not do what I expect?
+ <br> A: As above, note that <code>int8_t</code> and <code>uint8_t</code>
are actually chars and are formatted as such. To avoid this, cast to an
integer type first:
+
+<pre>lexical_cast<std::string>(static_cast<int>(n));</pre>
+
+ <p> Q: The implementation always resets the <code>ios_base::skipws</code>
flag of an underlying stream object. It breaks my <code>operator>></code>
that works only in presence of this flag. Can you remove code that resets the
flag?
+ <br> A: May be in a future version. There is no requirement in <a
href="#n1973">[N1973]</a> to reset the flag but remember that <a
href="#n1973">[N1973]</a> is not yet accepted by the committee. By the way,
it's a great opportunity to make your <code>operator>></code> conform to
the standard. Read a good C++ book, study <code>std::sentry</code> and <a
href="../../libs/io/doc/ios_state.html">ios_state_saver</a>.
+</ul>
+<h2><a name="references">References</h2>
+<ul type="square">
+ <a name="n1973"></a><li> [N1973] Kevlin Henney, Beman Dawes, Lexical
Conversion Library Proposal for TR2,
+ <a
href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1973.html";>N1973</a>.
+ <a name="tuning"></a><li> [Tuning] Alexander Nasonov, Fine Tuning for
lexical_cast,
+ <a
href="http://www.accu.org/var/uploads/journals/overload74.pdf";>Overload #74</a>,
+ August 2006.</li>
+</ul>
<h2><a name="changes">Changes</a></h2>
+<h3>August, October 2006:</h3>
+<ul type="square">
+ <li>Better performance for many combinations of <code>Source</code> and
<code>Target</code>
+ types. Refer to <a href="#tuning">[Tuning]</a> for more details.
+ </li>
+</ul>
<h3>June 2005:</h3>
<ul type="square">
<li>Call-by-const reference for the parameters. This requires partial
specialization
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