This template class describes an object that controls insertion of elements and encoded objects into a stream buffer with elements of type Elem, also known as char_type, whose character traits are determined by the class Tr, also known as traits_type.
For a list of all members of this type, see basic_ostream Members.
template <class _Elem, class _Tr = char_traits<Elem> >
class basic_ostream
: virtual public basic_ios<_Elem, _Tr>
Parameters
_Elem
A char_type._Tr
The character traits_type.
Remarks
Most of the member functions that overload operator<< are formatted output functions. They follow the pattern:
iostate state = goodbit;
const sentry ok( *this );
if ( ok )
{try
{<convert and insert elements
accumulate flags in state> }
catch ( ... )
{try
{setstate( badbit ); }
catch ( ... )
{}
if ( ( exceptions( ) & badbit ) != 0 )
throw; }}
width( 0 ); // Except for operator<<(Elem)
setstate( state );
return ( *this );
Two other member functions are unformatted output functions. They follow the pattern:
iostate state = goodbit;
const sentry ok( *this );
if ( !ok )
state |= badbit;
else
{try
{<obtain and insert elements
accumulate flags in state> }
catch ( ... )
{try
{setstate( badbit ); }
catch ( ... )
{}
if ( ( exceptions( ) & badbit ) != 0 )
throw; }}
setstate( state );
return ( *this );
Both groups of functions call setstate(badbit) if they encounter a failure while inserting elements.
An object of class basic_istream<Elem, Tr> stores only a virtual public base object of class basic_ios<Elem, Tr>.
Example
See the example for basic_ofstream Class to learn more about output streams.
Requirements
Header: <ostream>
Namespace: std
See Also
Reference
Thread Safety in the Standard C++ Library