113 lines
3.5 KiB
C++
113 lines
3.5 KiB
C++
// ----------------------------------------------------------------------------
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// sample_formats.cpp : example of basic usage of format
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// ----------------------------------------------------------------------------
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// Copyright Samuel Krempp 2003. Use, modification, and distribution are
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// subject to the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// See http://www.boost.org/libs/format for library home page
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// ----------------------------------------------------------------------------
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#include <iostream>
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#include <iomanip>
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#include <cassert>
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#include "boost/format.hpp"
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// 2 custom namespaces, to bring in a few useful names :
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namespace MyNS_ForOutput {
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using std::cout; using std::cerr;
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using std::string;
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using std::endl; using std::flush;
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using boost::format;
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using boost::io::group;
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}
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namespace MyNS_Manips {
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using std::setfill;
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using std::setw;
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using std::hex ;
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using std::dec ;
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// gcc-2.95 doesnt define the next ones
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// using std::showbase ;
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// using std::left ;
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// using std::right ;
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// using std::internal ;
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}
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int main(){
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using namespace MyNS_ForOutput;
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using namespace MyNS_Manips;
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std::cout << format("%|1$1| %|2$3|") % "Hello" % 3 << std::endl;
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// Reordering :
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cout << format("%1% %2% %3% %2% %1% \n") % "o" % "oo" % "O"; // 'simple' style.
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// prints "o oo O oo o \n"
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cout << format("(x,y) = (%1$+5d,%2$+5d) \n") % -23 % 35; // Posix-Printf style
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// No reordering :
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cout << format("writing %s, x=%s : %d-th step \n") % "toto" % 40.23 % 50;
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// prints "writing toto, x=40.23 : 50-th step \n"
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cout << format("(x,y) = (%+5d,%+5d) \n") % -23 % 35;
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cout << format("(x,y) = (%|+5|,%|+5|) \n") % -23 % 35;
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cout << format("(x,y) = (%|1$+5|,%|2$+5|) \n") % -23 % 35;
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// all those are the same, it prints "(x,y) = ( -23, +35) \n"
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// Using manipulators, via 'group' :
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cout << format("%2% %1% %2%\n") % 1 % group(setfill('X'), hex, setw(4), 16+3) ;
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// prints "XX13 1 XX13\n"
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// printf directives's type-flag can be used to pass formatting options :
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cout << format("_%1$4d_ is : _%1$#4x_, _%1$#4o_, and _%1$s_ by default\n") % 18;
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// prints "_ 18_ is : _0x12_, _ 022_, and _18_ by default\n"
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// Taking the string value :
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std::string s;
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s= str( format(" %d %d ") % 11 % 22 );
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assert( s == " 11 22 ");
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// -----------------------------------------------
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// %% prints '%'
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cout << format("%%##%#x ") % 20 << endl;
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// prints "%##0x14 "
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// -----------------------------------------------
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// Enforcing the right number of arguments
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// Too much arguments will throw an exception when feeding the unwanted argument :
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try {
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format(" %1% %1% ") % 101 % 102;
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// the format-string refers to ONE argument, twice. not 2 arguments.
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// thus giving 2 arguments is an error
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}
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catch (boost::io::too_many_args& exc) {
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cerr << exc.what() << "\n\t\t***Dont worry, that was planned\n";
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}
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// Too few arguments when requesting the result will also throw an exception :
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try {
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cerr << format(" %|3$| ") % 101;
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// even if %1$ and %2$ are not used, you should have given 3 arguments
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}
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catch (boost::io::too_few_args& exc) {
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cerr << exc.what() << "\n\t\t***Dont worry, that was planned\n";
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}
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cerr << "\n\nEverything went OK, exiting. \n";
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return 0;
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}
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