Defines several types and functions basic to the operation of iostreams. This header is typically included for you by another iostream headers; you rarely include it directly.
For a list of all members of this header, see <ios> Members.
A large group of functions are manipulators. A manipulator declared in <ios> alters the values stored in its argument object of class ios_base. Other manipulators perform actions on streams controlled by objects of a type derived from this class, such as a specialization of one of the template classes basic_istream or basic_ostream. For example, noskipws(str) clears the format flag ios_base::skipws in the object str, which can be of one of these types.
You can also call a manipulator by inserting it into an output stream or extracting it from an input stream, because of special insertion and extraction operations supplied for the classes derived from ios_base. For example:
istr >> noskipws;