#include <iostream>
#include <fstream>
 
void write(const char *filename)
{
   std::ofstream file(filename);
   for ( int i = 100; i < 110; ++i )
   {
      file << std::hex << i << '\n';
   }
}
 
void read(const char *filename)
{
   std::ifstream file(filename);
   int value;
   while ( file >> std::hex >> value )
   {
      std::cout << "value = " << value << '\n';
   }
}
 
int main()
{
   static const char filename[] = "file.txt";
   write(filename);
   read(filename);
   return 0;
}
 
/* my output
value = 100
value = 101
value = 102
value = 103
value = 104
value = 105
value = 106
value = 107
value = 108
value = 109
*/
 
/* file.txt
64
65
66
67
68
69
6a
6b
6c
6d
*/