cpp/io/basic stringbuf/basic stringbuf

@1@ Default constructor. It is implementation-defined whether the sequence pointers (eback, gptr, egptr, pbase, pptr, epptr) are initialized to null pointers.

@2@ Constructs a object: initializes the base class by calling the default constructor of std, initializes the character sequence with an empty string, and sets the mode to.

@3@ Constructs a object by performing the same initialization as, followed by initializing the associated character sequence as if by calling str.

@4@ The copy constructor is deleted; is not.

@5@ Move-constructs a object by moving all state from another  object, including the associated string, the open mode, the locale, and all other state. After the move, the six pointers of std in are guaranteed to be different from the corresponding pointers in the moved-from  unless null.

@6,7@ Same as, except that is used to construct the associated string.

@8@ Same as, except that is used to construct the associated string.

@9,10@ Constructs a object by performing the same initialization as, followed by initializing the associated string with content of , using  as its allocator.

@11@ Same as, except the type of 's allocator is not. .

@12@ Same as, except that is used to construct the associated string.