For die-hard boost::lexical_cast users or as a transitional path to boost::convert, one of boost::convert deployments is not that different from boost::lexical_cast. In fact, the original boost::lexical_cast functionality is easily deployed through boost::convert interface:

#include <boost/convert.hpp>
#include <boost/convert/lexical_cast.hpp>

using std::string;
using boost::lexical_cast;
using boost::convert;

// Definition of the default converter (optional)
struct boost::cnv::by_default : boost::cnv::lexical_cast {};

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;
}

Important

As we explore boost::convert behavior and interface further, at first they might appear unduly complex, verbose, etc... nothing like atoi()... so famous for all the wrong reasons. :-) It is important to remember that a conversion request is only a request which may succeed but may also fail... which might not be as rare or as exceptional as one might hope. boost::convert (as well as boost::lexical_cast) behavior and interfaces reflect that reality.