2 Beispiele

#include <iostream.h>
main(){
  char c;
  while(cin >> c){
      cout << c << c << flush;
  }
  cout << endl;
}

#include <iostream.h>
main(){
  char c;
  while(cin.read(&c,1)){
    if(c=='\n') 
      cout << endl;
    else
      cout << c << c << flush;
  }
  cout << endl;
}