#include <iostream.h>
#include <ctype.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{ char c;
  streampos pos;
      if ( argc != 2 )
         cerr << argv[0] << " takes one argument only\n";
      fstream fio(argv[1], ios::in | ios::app);
      if ( ! fio )
      {   cerr << argv[0] << ':' << " Cannot open"
                          << argv[1] << " for updating\n",
          exit(1);
      }
      fio.seekg(0);
      while ((c = fio.get()) != EOF) 
          if ( isupper(c) )
          {   // fio.seekp(-1, ios::cur);   // position for writing c
              cout << c;
              pos = fio.tellg();
              fio.put(tolower(c));          // always at end of file
              fio.seekg(pos);
          }
      fio.close();
}