Causes output to be processed when the buffer is not empty.
ios_base& unitbuf( 
   ios_base& _Str 
);
Parameters
- _Str
A reference to an object of type ios_base, or to a type that inherits from ios_base. 
Return Value
A reference to the object from which _Str is derived.
Remarks
Note that endl also flushes the buffer.
nounitbuf is in effect by default.
The manipulator effectively calls _Str.setf(ios_base::unitbuf), and then returns _Str.
Requirements
Header: <ios>
Namespace: std