str
Syntax:
  #include <sstream>
  void str( string s );
  string str();

The function str() can be used in two ways. First, it can be used to get a copy of the string that is being manipulated by the current stream string. This is most useful with output strings. For example:

  ostringstream stream1;
  stream1 << "Testing!" << endl;
  cout << stream1.str();

Second, str() can be used to copy a string into the stream. This is most useful with input strings. For example:

  istringstream stream1;
  string string1 = "25";
  stream1.str(string1);

str() is also handy when you need to clear the stream so that it can be reused:

  ostringstream stream1;
  stream1 << "Using this once" << endl;
  cout << stream1.str();
  stream1.str("");  // Clear the stream
  stream1 << "Now, using it twice" << endl;
  cout << stream1.str();