#include <iostream>
using std::cout;
#include <fstream>
using std::ifstream;
#include <string>
using std::string;
using std::getline;
 
int main()
{
   ifstream myfile("test.txt");
   string line, buffer[10];
   const size_t size = sizeof buffer / sizeof *buffer;
   size_t i = 0;
   /*
    * Read all lines of file, putting them into
    * a circular buffer of strings.
    */
   while ( getline(myfile, line) )
   {
      buffer[i] = line;
      if ( ++i >= size )
      {
         i = 0;
      }
   }
   /*
    * Print the lines.
    */
   for ( size_t j = 0; j < size; ++j )
   {
      cout << buffer[i] << "\n";
      if ( ++i >= size )
      {
         i = 0;
      }
   }
   return 0;
}

#include <iostream>
using std::cout;
#include <fstream>
using std::ifstream;
#include <string>
using std::string;
using std::getline;
 
size_t count_lines(const char *filename)
{
   ifstream myfile("test.txt");
   string line;
   size_t count = 0;
   while ( getline(myfile, line) )
   {
      ++count;
   }
   return count;
}
 
int main()
{
   const char filename[] = "test.txt";
   size_t i, count = count_lines(filename);
   ifstream myfile(filename);
   string line;
   for ( i = 0; i < count - 10; ++i )
   {
      getline(myfile, line); /* read and discard: skip line */
   }
   while ( getline(myfile, line) )
   {
      cout << line << "\n";
   }
   return 0;
}