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  1. #include <limits>       // std::numeric_limits
  2. #include <algorithm>    // std::reverse
  3.  
  4. namespace cppx {
  5.     using std::numeric_limits;
  6.     using std::reverse;
  7.  
  8.     typedef numeric_limits<long>    Long_info;
  9.     int const long_digits   = Long_info::max_digits10;
  10.     int const long_bufsize  = long_digits + 2;
  11.  
  12.     inline void unsigned_to_decimal( unsigned long number, char* buffer )
  13.     {
  14.         if( number == 0 )
  15.         {
  16.             *buffer++ = '0';
  17.         }
  18.         else
  19.         {
  20.             char* p_first = buffer;
  21.             while( number != 0 )
  22.             {
  23.                 *buffer++ = '0' + number % 10;
  24.                 number /= 10;
  25.             }
  26.             reverse( p_first, buffer );
  27.         }
  28.         *buffer = '\0';
  29.     }
  30.  
  31.     inline auto decimal_from_unsigned( unsigned long number, char* buffer )
  32.         -> char const*
  33.     {
  34.         unsigned_to_decimal( number, buffer );
  35.         return buffer;
  36.     }
  37.  
  38.     inline void to_decimal( long number, char* buffer )
  39.     {
  40.         if( number < 0 )
  41.         {
  42.             buffer[0] = '-';
  43.             unsigned_to_decimal( -number, buffer + 1 );
  44.         }
  45.         else
  46.         {
  47.             unsigned_to_decimal( number, buffer );
  48.         }
  49.     }
  50.  
  51.     inline auto decimal_from( long number, char* buffer )
  52.         -> char const*
  53.     {
  54.         to_decimal( number, buffer );
  55.         return buffer;
  56.     }
  57. }  // namespace cppx
  58.  
  59. #include <iostream>
  60. using namespace std;
  61.  
  62. auto main() -> int
  63. {
  64.     using cppx::decimal_from;
  65.     using cppx::long_bufsize;
  66.     using cppx::Long_info;
  67.  
  68.     char spec[long_bufsize];
  69.  
  70.     cout << decimal_from( Long_info::min(), spec ) << endl;
  71.     cout << decimal_from( Long_info::min() + 1, spec ) << endl;
  72.     cout << decimal_from( 0, spec ) << endl;
  73.     cout << decimal_from( Long_info::max() - 1, spec ) << endl;
  74.     cout << decimal_from( Long_info::max(), spec ) << endl;
  75. }
  76.  
Success #stdin #stdout 0s 3340KB
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-2147483648
-2147483647
0
2147483646
2147483647
https://ideone.com/nrQfA8
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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