[Valmont]

does anyone know how to read in a steam of charactes, on after another, one at a time, and build a sentence out of them

Is this what you mean?

#include <iostream>
#include <cstdlib>
#include <string>

using namespace std;

int main(int argc, char *argv[])
{
   string letters;
   string input;
   unsigned count(0);
   
   for(;;)
   {
      //Use getline so spaces and tabs are counted in.
      getline(cin, input, '\n');
      if(input[0] == '@') //@ terminates the input sequence.
         break;
      else
      {
         //Add only ONE single letter. Ignore the rest.
         letters+=input[0];
      }
   }
   cout<<letters<<endl;

   system("PAUSE");
   return 0;
}

If so, then try the rest of your assignment for yourself first. It's a nice excercise.