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  1. #include <iostream>
  2. #include <iomanip>
  3.  
  4. int main()
  5. {
  6.     const auto coutwf = [] () -> std::ostream&
  7.     { return std::cout << std::setw(20) << std::setfill('0') ; } ;
  8.  
  9.     constexpr double d = 12345678.9 ;
  10.     coutwf() << d << '\n' ; // 000000001.23457e+007
  11.  
  12.     // save the current format flags associated with std::cout
  13.     const auto original_flags = std::cout.flags() ;
  14.  
  15.     // set flag: use fixed notation for floating point types
  16.     // set flag: prefix non-negative numeric output with a '+'
  17.     // leave all other format flags unchanged
  18.     std::cout.setf( std::ios::fixed | std::ios::showpos ) ;
  19.     coutwf() << d << '\n' ; // 0000+12345678.900000
  20.  
  21.     // set: use internal justification
  22.     // unset: left justification, right justification
  23.     // leave all other format flags unchanged
  24.     std::cout.setf( std::ios::internal, std::ios::adjustfield ) ;
  25.     coutwf() << d << '\n' ; // +000012345678.900000
  26.  
  27.     // set: use left justification
  28.     // unset: right justification, internal justification
  29.     // leave all other format flags unchanged
  30.     std::cout.setf( std::ios::left, std::ios::adjustfield ) ;
  31.     coutwf() << d << '\n' ; // +12345678.9000000000
  32.  
  33.     // replace *all* flags with the original flags
  34.     std::cout.flags(original_flags) ;
  35.     coutwf() << d << '\n' ; // 000000001.23457e+007
  36. }
  37.  
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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0000000001.23457e+07
0000+12345678.900000
+000012345678.900000
+12345678.9000000000
0000000001.23457e+07
https://ideone.com/C9UmBr
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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