The GNU C++ Iostream Library



3.1: Shared properties: class ios

The base class ios provides methods to test and manage the state of input or output streams.

ios delegates the job of actually reading and writing bytes to the abstract class streambuf, which is designed to provide buffered streams (compatible with C, in the GNU implementation). See Streambuf, for information on the facilities available at the streambuf level.


Constructor:  ios::ios ([streambuf* sb [, ostream* tie])

The ios constructor by default initializes a new ios, and if you supply a streambuf sb to associate with it, sets the state good in the new ios object. It also sets the default properties of the new object.

You can also supply an optional second argument tie to the constructor: if present, it is an initial value for ios::tie, to associate the new ios object with another stream.


Destructor:  ios::~ios ()

The ios destructor is virtual, permitting application-specific behavior when a stream is closed---typically, the destructor frees any storage associated with the stream and releases any other associated objects.

  • States Checking the state of a stream.
  • Format Control Choices in formatting.
  • Manipulators Convenient ways of changing stream properties.
  • Advanced Features Extensions, synchronization and the streambuf.


  • Translated 02/24/96 by Rance Necaise. Original texi file by Bothner and Pesch.