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  1. #include <iostream>
  2. #include <cstdint>
  3. #include <bitset>
  4. #include <cstring>
  5. #include <algorithm>
  6.  
  7. struct bits
  8. {
  9.     unsigned sender : 16 ;
  10.     unsigned res : 16 ;
  11.     unsigned e : 12 ;
  12.     unsigned f : 4 ;
  13. };
  14.  
  15. int main()
  16. {
  17.     const bits b { 0xffff, 3, 2, 1 } ;
  18.  
  19.     const std::uint32_t res = b.res ;
  20.     const std::uint32_t e = b.e ;
  21.     const std::uint32_t f = b.f ;
  22.  
  23.     std::uint32_t buff = ( res << 16 ) | ( e << 4 ) | f ;
  24.     // test it
  25.     std::cout << std::bitset<32>(buff) << '\n' ;
  26.  
  27.     // copy it
  28.     std::uint8_t byte_buff[4] ;
  29.     std::memcpy( byte_buff, &buff, sizeof(buff) ) ;
  30.  
  31.     // check endianness
  32.     for( std::uint8_t b : byte_buff ) std::cout << std::bitset<8>(b) << ' ' ;
  33.     std::cout << '\n' ;
  34.  
  35.     // if needed, swap bytes
  36.     std::swap( byte_buff[0], byte_buff[3] ) ;
  37.     std::swap( byte_buff[1], byte_buff[2] ) ;
  38.  
  39.     for( std::uint8_t b : byte_buff ) std::cout << std::bitset<8>(b) << ' ' ;
  40.     std::cout << '\n' ;
  41. }
  42.  
Success #stdin #stdout 0s 2988KB
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stdin
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Standard input is empty
stdout
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00000000000000110000000000100001
00100001 00000000 00000011 00000000 
00000000 00000011 00000000 00100001
https://ideone.com/rb9Azj
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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