21. String Stream

• 
      #include <cassert>
      #include <string> 
      #include <sstream> 
      int main()
      {
          const double PI = 3.1415926;
          double value;
          std::stringstream  buffer;  // text buffer
          buffer.precision( 8 );      // increase default precision (*)
          buffer << PI;               // formatted output  
          buffer >> value;            // formatted input
          assert( PI == value );
          std::string text; 
          text = buffer.str( );  // returns std::string  
          buffer.str( "" );      // clear buffer  
          return 0;
      }
  
  

  (*) try commenting out precision change and see what happens