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  1. #include <iostream>
  2. #include <string>
  3. #include <sstream>
  4. #include <iomanip>
  5. //#include <boost/format.hpp>
  6.  
  7.  
  8. std::string format( double d, int place )
  9. {
  10.     std::ostringstream ss;
  11.     ss << std::fixed << std::setprecision(place) << d ;
  12.     return ss.str() ;
  13. }
  14.  
  15. struct format_a
  16. {
  17.     format_a( double d, int place ) : value(d), prec(place) {}
  18.  
  19.     const double value ;
  20.     const int prec ;
  21. };
  22.  
  23. template < typename OSTREAM >
  24. OSTREAM& operator<< ( OSTREAM& stm, const format_a& fmt )
  25. { return stm << std::fixed << std::setprecision(fmt.prec) << fmt.value ; }
  26.  
  27. struct format_b
  28. {
  29.     explicit format_b( int place, int w = 0, char f = ' ' )
  30.              : prec(place), width(w), fill(f) {}
  31.  
  32.     template < typename T > format_b& operator% ( const T& v )
  33.     {
  34.         std::ostringstream ss;
  35.         ss << std::fixed << std::setprecision(prec)
  36.            << std::setw(width) << std::setfill(fill) << v ;
  37.         chars_out += ss.str() ;
  38.         return *this ;
  39.     }
  40.  
  41.     const int prec ;
  42.     const int width ;
  43.     const char fill ;
  44.     std::string chars_out ;
  45. };
  46.  
  47. template < typename OSTREAM >
  48. OSTREAM& operator<< ( OSTREAM& stm, const format_b& fmt )
  49. { for( char c : fmt.chars_out ) stm << stm.widen(c) ; return stm ; }
  50.  
  51.  
  52. int main ()
  53. {
  54.   std::cout << format( .0123456789, 2 ) << '\n' ;
  55.   std::cout << format( 11.1123456789, 5 ) << '\n' ;
  56.  
  57.   std::cout << format_a( 1234.2123456789, 3 ) << '\n' ;
  58.   std::wcout << format_a( 1234.3123456789, 2 ) << '\n' ;
  59.  
  60.   std::cout << format_b(3) % 1234.2123456789 << '\n' ;
  61.   std::wcout << format_b( 2, 9 ) % "values:" % 999.999 % 1234.3123456789 % '\n' ;
  62.  
  63.   // double x = 7.40200133400;
  64.   // std::cout << boost::format("%1$.2f")%x << '\n' ;
  65. }
  66.  
Success #stdin #stdout 0s 3480KB
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stdin
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Standard input is empty
stdout
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0.01
11.11235
1234.212
1234.31
1234.212
  values:  1000.00  1234.31
https://ideone.com/MQAufS
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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