ssbuf(3C)

NAME
     strstreambuf - streambuf specialized to arrays

SYNOPSIS
     #include <iostream.h>
     #include <strstream.h>

     class strstreambuf : public streambuf {
     public:
               strstreambuf() ;
               strstreambuf(char*, int, char*);
               strstreambuf(int);
               strstreambuf(unsigned char*, int, unsigned char*);
               strstreambuf(void* (*a)(long), void(*f)(void*));

          void freeze(int n=1) ;
          char*     str();
          virtual streambuf*  setbuf(char*, int)
     };

DESCRIPTION
     A strstreambuf is a streambuf that uses an array of bytes (a string)
     to hold the sequence of characters.  Given the convention that a char*
     should be interpreted as pointing just before the char it really
     points at, the mapping between the abstract get/put pointers (see
     sbuf.pub(3C)) and char* pointers is direct.  Moving the pointers
     corresponds exactly to incrementing and decrementing the char* values.

     To accommodate the need for arbitrary length strings, strstreambuf
     supports a dynamic mode.  When a strstreambuf is in dynamic mode,
     space for the character sequence is allocated as needed.  When the
     sequence is extended too far, it will be copied to a new array.

     The following descriptions make the following assumptions:

     * ssb is a strstreambuf*.

     * n is an int.

     * ptr and pstart are char*s or unsigned char*s.

     * a is a void* (*)(long).

     * f is a void* (*)(void*).

   Constructors
     strstreambuf()
          Constructs an empty strstreambuf in dynamic mode.  This means
          that space will be automatically allocated to accommodate the
          characters that are put into the strstreambuf (using operators
          new and delete).  Because this may require copying the original
          characters, it is recommended that when many characters are to be
          inserted, the program should use setbuf() (described on this man
          page) to inform the strstreambuf.

     strstreambuf(a, f)
          Constructs an empty strstreambuf in dynamic mode.  a is used as
          the allocator function in dynamic mode.  The argument passed to a
          will be a long denoting the number of bytes to be allocated.  If
          a is null, operator new will be used.  f is used to free (or
          delete) areas returned by a.  The argument to f will be a pointer
          to the array allocated by a.  If f is null, operator delete is
          used.

     strstreambuf(n)
          Constructs an empty strstreambuf in dynamic mode.  The initial
          allocation of space will be at least n bytes.

     strstreambuf(ptr, n, pstart)
          Constructs a strstreambuf to use the bytes starting at ptr.  The
          strstreambuf will be in static mode; it will not grow
          dynamically.  If n is positive, then the n bytes starting at ptr
          are used as the strstreambuf.  If n is zero, ptr is assumed to
          point to the beginning of a null terminated string and the bytes
          of that string (not including the terminating null character)
          will constitute the strstreambuf.  If n is negative, the
          strstreambuf is assumed to continue indefinitely.  The get
          pointer is initialized to ptr.  The put pointer is initialized to
          pstart.  If pstart is null, then stores will be treated as
          errors.  If pstart is non-null, then the initial sequence for
          fetching (the get area) consists of the bytes between ptr and
          pstart.  If pstart is null, then the initial get area consists of
          the entire array.

   Member Functions
     ssb->freeze(n)
          Inhibits (when n is nonzero) or permits (when n is zero)
          automatic deletion of the current array.  Deletion normally
          occurs when more space is needed or when ssb is being destroyed.
          Only space obtained via dynamic allocation is ever freed.  It is
          an error (and the effect is undefined) to store characters into a
          strstreambuf that was in dynamic allocation mode and is now
          frozen.  It is possible, however, to thaw (unfreeze) such a
          strstreambuf and resume storing characters.

     ptr=ssb->str()
          Returns a pointer to the first char of the current array and
          freezes ssb.  If ssb was constructed with an explicit array, ptr
          will point to that array.  If ssb is in dynamic allocation mode,
          but nothing has yet been stored, ptr may be null.

     ssb->setbuf(0,n)
          ssb remembers n and the next time it does a dynamic mode
          allocation, it makes sure that at least n bytes are allocated.

SEE ALSO
     sbuf.pub(3C), strstream(3C)