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- // Copyright (c) 2009-2016 Vladimir Batov.
- // Use, modification and distribution are subject to the Boost Software License,
- // Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
- #ifdef _MSC_VER
- # pragma warning(disable : 4127) // conditional expression is constant.
- # pragma warning(disable : 4189) // local variable is initialized but not referenced.
- # pragma warning(disable : 4100) // unreferenced formal parameter.
- # pragma warning(disable : 4714) // marked as __forceinline not inlined.
- #endif
- namespace { namespace local
- {
- #if defined(_MSC_VER)
- static bool const is_msc = true;
- #else
- static bool const is_msc = false;
- #endif
- }}
- #include <boost/bind.hpp>
- #include <boost/detail/lightweight_test.hpp>
- static
- void
- log(char const*)
- {
- // Dummy function to demonstrate how problems might be logged.
- }
- //[getting_started_headers1
- #include <boost/convert.hpp>
- #include <boost/convert/lexical_cast.hpp>
- //]
- //[getting_started_using
- using std::string;
- using boost::lexical_cast;
- using boost::convert;
- //]
- //[getting_started_default_converter
- // Definition of the default converter (optional)
- struct boost::cnv::by_default : boost::cnv::lexical_cast {};
- //]
- static
- void
- getting_started_example1()
- {
- //[getting_started_example1
- try
- {
- boost::cnv::lexical_cast cnv; // boost::lexical_cast-based converter
- int i1 = lexical_cast<int>("123"); // boost::lexical_cast standard deployment
- int i2 = convert<int>("123").value(); // boost::convert with the default converter
- int i3 = convert<int>("123", cnv).value(); // boost::convert with an explicit converter
- string s1 = lexical_cast<string>(123); // boost::lexical_cast standard deployment
- string s2 = convert<string>(123).value(); // boost::convert with the default converter
- string s3 = convert<string>(123, cnv).value(); // boost::convert with an explicit converter
- BOOST_TEST(i1 == 123);
- BOOST_TEST(i2 == 123);
- BOOST_TEST(i3 == 123);
- BOOST_TEST(s1 == "123");
- BOOST_TEST(s2 == "123");
- BOOST_TEST(s3 == "123");
- }
- catch (std::exception const& ex)
- {
- // Please be aware that the conversion requests above can fail.
- // Use try'n'catch blocks to handle any exceptions thrown.
- // Ignore this at your peril!
- std::cerr << "Exception " << ex.what() << std::endl;
- }
- //] [/getting_started_example1]
- }
- static
- void
- getting_started_example2()
- {
- //[getting_started_example2
- // Does not throw. Returns fallback value (-1) when failed.
- int i = convert<int>("uhm", boost::cnv::lexical_cast()).value_or(-1);
- BOOST_TEST(i == -1); // Conversion failed. 'i' assigned the fallback value.
- //]
- }
- //[getting_started_headers3
- #include <boost/convert/strtol.hpp>
- #include <boost/convert/spirit.hpp>
- //]
- static
- void
- getting_started_example3()
- {
- //[getting_started_example3
- boost::cnv::lexical_cast cnv1;
- boost::cnv::strtol cnv2;
- boost::cnv::spirit cnv3;
- int i1 = convert<int>("123", cnv1).value();
- int i2 = convert<int>("123", cnv2).value(); // Two times faster than lexical_cast.
- int i3 = convert<int>("123", cnv3).value(); // Four times faster than lexical_cast.
- //]
- }
- //[getting_started_headers4
- #include <boost/convert/stream.hpp>
- //]
- static
- void
- getting_started_example4()
- {
- //[getting_started_example4
- boost::cnv::cstream cnv;
- try
- {
- int i1 = lexical_cast<int>(" 123"); // Does not work.
- BOOST_TEST(!"Never reached");
- }
- catch (...) {}
- int i2 = convert<int>(" 123", cnv(std::skipws)).value(); // Success
- string s1 = lexical_cast<string>(12.34567);
- string s2 = convert<string>(12.34567, cnv(std::fixed)(std::setprecision(3))).value();
- string s3 = convert<string>(12.34567, cnv(std::scientific)(std::setprecision(3))).value();
- string expected = local::is_msc ? "1.235e+001" : "1.235e+01";
- BOOST_TEST(i2 == 123); // boost::cnv::cstream. Successful conversion of " 123".
- BOOST_TEST(s1 == "12.34567"); // boost::lexical_cast. Precision is not configurable.
- BOOST_TEST(s2 == "12.346"); // boost::cnv::cstream. Precision was set to 3. Fixed.
- BOOST_TEST(s3 == expected); // boost::cnv::cstream. Precision was set to 3. Scientific.
- //]
- }
- static
- void
- getting_started_example5()
- {
- //[getting_started_example5
- boost::cnv::cstream cnv;
- int i1 = lexical_cast<int>("123"); // Throws when conversion fails.
- int i2 = convert<int>("123", cnv).value(); // Throws when conversion fails.
- int i3 = convert<int>("uhm", cnv).value_or(-1); // Returns -1 when conversion fails.
- BOOST_TEST(i1 == 123);
- BOOST_TEST(i2 == 123);
- BOOST_TEST(i3 == -1);
- //]
- }
- static
- void
- getting_started_example6()
- {
- std::string const s1 = "123";
- std::string const s2 = "456";
- int const default_i1 = 11;
- int const default_i2 = 12;
- boost::cnv::cstream cnv;
- //[getting_started_example6
- int i1 = convert<int>(s1, cnv(std::hex)).value_or(-1); // Read as hex
- int i2 = convert<int>(s2, cnv(std::dec)).value_or(-1); // Read as decimal
- if (i1 == -1) log("bad i1"), i1 = default_i1; // Log failure. Proceed with the default
- if (i2 == -1) log("bad i2"), i2 = default_i2; // Log failure. Proceed with the default
- // ... proceed
- //]
- BOOST_TEST(i1 == 291);
- BOOST_TEST(i2 == 456);
- }
- static
- void
- getting_started_example7()
- {
- std::string const s1 = "123";
- std::string const s2 = "456";
- int const default_i1 = 11;
- int const default_i2 = 12;
- boost::cnv::cstream cnv;
- //[getting_started_example7
- int i1 = convert<int>(s1, cnv(std::hex)).value_or(default_i1); // If failed, proceed with the default
- int i2 = convert<int>(s2, cnv(std::dec)).value_or(default_i2); // If failed, proceed with the default
- // ... proceed
- //]
- BOOST_TEST(i1 == 291);
- BOOST_TEST(i2 == 456);
- }
- static
- //[getting_started_example9_func
- int
- fallback_fun(char const* msg, int fallback_value)
- {
- // The principal advantage of a fallback_func over a fallback_value
- // is that the former is only called when the conversion request fails.
- // Consequently, the returned fallback_value is only calculated (which
- // potentially might be expensive) when it is absolutely necessary.
- log(msg); return fallback_value;
- }
- //]
- static
- void
- getting_started_example9()
- {
- std::string const s1 = "123";
- std::string const s2 = "456";
- int const default_i1 = 11;
- int const default_i2 = 12;
- //[getting_started_example9
- int i1 = convert<int>(s1).value_or_eval(boost::bind(fallback_fun, "bad i1", default_i1));
- int i2 = convert<int>(s2).value_or_eval(boost::bind(fallback_fun, "bad i2", default_i2));
- // ... proceed
- //]
- BOOST_TEST(i1 == 123);
- BOOST_TEST(i2 == 456);
- }
- static
- void
- getting_started_example8()
- {
- std::string const str = "123";
- int const default_i1 = 12;
- //[getting_started_example8
- int i1 = default_i1;
- try
- {
- i1 = lexical_cast<int>(str);
- }
- catch (...)
- {
- log("bad i1");
- }
- //]
- BOOST_TEST(i1 == 123);
- }
- int
- main(int, char const* [])
- {
- getting_started_example1();
- getting_started_example2();
- getting_started_example3();
- getting_started_example4();
- getting_started_example5();
- getting_started_example6();
- getting_started_example7();
- getting_started_example8();
- getting_started_example9();
- return boost::report_errors();
- }
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