// -*- C++ -*- // Boost general library 'format' --------------------------- // See http://www.boost.org for updates, documentation, and revision history. // (C) Samuel Krempp 2001 // krempp@crans.ens-cachan.fr // Permission to copy, use, modify, sell and // distribute this software is granted provided this copyright notice appears // in all copies. This software is provided "as is" without express or implied // warranty, and with no claim as to its suitability for any purpose. // ------------------------------------------------------------------------------ // sample_advanced.cc : examples of adanced usage of format // ------------------------------------------------------------------------------ #include #include #include "boost/format.hpp" int main(){ using namespace std; using boost::format; using boost::io::group; using boost::io::str; string s; stringstream oss; //------------------------------------------------------------------------ // storing the parsed format-string in a 'formatter' : // format objects are regular objects that can be copied, assigned, // fed arguments, dumped to a stream, re-fed arguments, etc... // So users can use them the way they like. format fmter("%1% %2% %3% %1% \n"); fmter % 10 % 20 % 30; cout << fmter; // prints "10 20 30 10 \n" // note that once the fmter got all its arguments, // the formatted string stays available (until next call to '%') // The result is available via function str() or stream's << : cout << fmter; // prints the same string again. // once you call operator% again, arguments are cleared inside the object // and it is an error to ask for the conversion string before feeding all arguments : fmter % 1001; try { cout << fmter; } catch (boost::io::too_few_args& exc) { cout << exc.what() << "***Dont worry, that was planned\n"; } // we just need to feed the last two arguments, and it will be ready for output again : cout << fmter % 1002 % 1003; // prints "1001 1002 1003 1001 \n" cout << fmter % 10 % 1 % 2; // prints "10 1 2 10 \n" //--------------------------------------------------------------- // using format objects // modify the formatting options for a given directive : fmter = format("%1% %2% %3% %2% %1% \n"); fmter.modify_item(4, group(setfill('_'), hex, showbase, setw(5)) ); cout << fmter % 1 % 2 % 3; // prints "1 2 3 __0x2 1 \n" // bind one of the argumets : fmter.bind_arg(1, 18); cout << fmter % group(hex, showbase, 20) % 30; // %2 is 20, and 20 == 0x14 // prints "18 0x14 30 _0x14 18 \n" fmter.modify_item(4, setw(0)); // cancels previous width-5 fmter.bind_arg(1, 77); // replace 18 with 77 for first argument. cout << fmter % 10 % 20; // prints "77 10 20 0xa 77 \n" try { cout << fmter % 6 % 7 % 8; // Aye ! too many args, because arg1 is bound already } catch (boost::io::too_many_args& exc) { cout << exc.what() << "***Dont worry, that was planned\n"; } // clear() clears regular arguments, but not bound arguments : fmter.clear(); cout << fmter % 2 % 3; // prints "77 2 3 0x2 77 \n" // use clear_binds() to clear both regular AND bound arguments : fmter.clear_binds(); cout << fmter % 1 % 2 % 3; // prints "1 2 3 0x2 1 \n" // setting desired exceptions : fmter.exceptions( boost::io::all_error_bits ^( boost::io::too_many_args_bit ) ); cout << fmter % 1 % 2 % 3 % 4 % 5 % 6 ; // ----------------------------------------------------------- // misc: // unsupported printf directives %n and asterisk-fields are purely ignored. // do *NOT* provide an argument for them, it is an error. cout << format("|%5d| %n") % 7 << endl; // prints "| 7| " cout << format("|%*.*d|") % 7 << endl; // prints "|7|" // truncations of strings : cout << format("%|.2s| %|8c|.\n") % "root" % "user"; // prints "ro u.\n" // manipulators conflicting with format-string : manipulators win. cout << format("%2s") % group(setfill('0'), setw(6), 1) << endl; // prints "000001" cout << format("%2$5s %1% %2$3s\n") % 1 % group(setfill('X'), setw(4), 2) ; // prints "XXX2 1 XXX2\n" // width is 4, as set by manip, not the format-string. // nesting : cout << format("%2$014x [%1%] %2$05s\n") % (format("%05s / %s") % -18 % 7) % group(showbase, -100); // prints "0x0000ffffff9c [-0018 / 7] -0100\n" cout << "\n\nEverything went OK, exiting. \n"; return 0; }