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  1. #include <iostream>
  2. #include <fstream>
  3.  
  4. union dbl {
  5.   char mem[8];
  6.   double d;
  7. };
  8.  
  9. int main()
  10. {
  11.   double d[] = {1.0, 2.1, 3.2, 4.3};
  12.  
  13.   std::ofstream fout("dataset.dat", std::ios::binary);
  14.   for (double* dp = d; dp != &d[sizeof(d) / sizeof(d[0])]; dp++)
  15.     fout.write(reinterpret_cast<char*>(dp), static_cast<std::streamsize>(sizeof(double)));
  16.   fout.close();
  17.  
  18.   std::ifstream fin("dataset.dat", std::ios::binary);
  19.   std::istreambuf_iterator<char> buf(fin), eof;
  20.  
  21.   for (; buf != eof;) {
  22.     dbl c;
  23.     c.mem[0] = *buf++;
  24.     c.mem[1] = *buf++;
  25.     c.mem[2] = *buf++;
  26.     c.mem[3] = *buf++;
  27.     c.mem[4] = *buf++;
  28.     c.mem[5] = *buf++;
  29.     c.mem[6] = *buf++;
  30.     c.mem[7] = *buf++;
  31.     std::cout << c.d << std::endl;
  32.   }
  33. }
  34.  
Success #stdin #stdout 0.01s 2856KB
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https://ideone.com/1VVS0T
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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