A related collection of methods allows you to extend this collection of flags and parameters for your own applications, without risk of conflict between them:
Method: static fmtflags ios::bitalloc ()
Reserve a bit (the single bit on in the result) to use as a flag. Using
bitalloc guards against conflict between two packages that use
ios objects for different purposes.
This method is available for upward compatibility, but is not in the
ANSI working paper. The number of bits available is limited; a
return value of 0 means no bit is available.
Method: static int ios::xalloc ()
Reserve space for a long integer or pointer parameter. The result is a
unique nonnegative integer. You can use it as an index to
ios::iword or ios::pword. Use xalloc to arrange
for arbitrary special-purpose data in your ios objects, without
risk of conflict between packages designed for different purposes.
Method: long& ios::iword (int index)
Return a reference to arbitrary data, of long integer type, stored in an
ios instance. index, conventionally returned from
ios::xalloc, identifies what particular data you need.
Method: long ios::iword (int index) const
Return the actual value of a long integer stored in an ios.
Method: void*& ios::pword (int index)
Return a reference to an arbitrary pointer, stored in an ios
instance. index, originally returned from ios::xalloc,
identifies what particular pointer you need.
Method: void* ios::pword (int index) const
Return the actual value of a pointer stored in an ios.