Make a separate folder for lexical_casts examples, use those examples in documenation and assure that they successfully build and run (refs #9046)

[SVN r85828]

example/small_examples.cpp

@@ -0,0 +1,52 @@
+// Copyright 2013 Antony Polukhin
+
+// Distributed under the Boost Software License, Version 1.0.
+// (See the accompanying file LICENSE_1_0.txt
+// or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
+
+#include <boost/lexical_cast.hpp>
+#include <string>
+#include <cstdio>
+
+//[lexical_cast_log_errno
+//`The following example uses numeric data in a string expression: 
+
+void log_message(const std::string &);
+
+void log_errno(int yoko)
+{
+    log_message("Error " + boost::lexical_cast<std::string>(yoko) + ": " + strerror(yoko));
+}
+
+//] [/lexical_cast_log_errno]
+
+
+//[lexical_cast_fixed_buffer
+//`The following example converts some number and puts it to file:
+
+void number_to_file(int number, FILE* file)
+{
+    typedef boost::array<char, 50> buf_t; // You can use std::array if your compiler supports it
+    buf_t buffer = boost::lexical_cast<buf_t>(number); // No dynamic memory allocation
+    fputs(buffer.begin(), file);
+}
+
+//] [/lexical_cast_fixed_buffer]
+
+//[lexical_cast_substring_conversion
+//`The following example takes part of the string and converts it to `int`:
+
+int convert_strings_part(const std::string& s, std::size_t pos, std::size_t n)
+{
+    return boost::lexical_cast<int>(s.data() + pos, n);
+}
+
+//] [/lexical_cast_substring_conversion]
+
+void log_message(const std::string &) {}
+
+int main()
+{
+    return 0;
+}
+