STRSTREAM(3CC4)STRSTREAM(3CC4)NAMEstrstream - stream class for ``I/O'' using character arrays
SYNOPSIS
#include <strstream.h>
class ios {
public:
enum open_mode { in, out, ate, app, trunc, nocreate, noreplace };
// see ios(3CC4) for remainder ...
};
#include <strstream.h> // includes <iostream.h>
class strstreambuf : public streambuf {
// see strstreambuf(3C++) ...
};
class strstreambase : virtual public ios {
// implementation detail of the Xstream classes ...
};
class istrstream : public strstreambase, public istream {
public:
istrstream(char* ptr);
istrstream(char* ptr, int len);
strstreambuf* rdbuf();
};
class ostrstream : public strstreambase, public ostream {
public:
ostrstream(char* ptr, int len, int mode=ios::out);
ostrstream();
strstreambuf* rdbuf();
int pcount();
char* str();
};
class strstream : public strstreambase, public iostream {
public:
strstream();
strstream(char* ptr, int len, int mode);
strstreambuf* rdbuf();
char* str();
};
DESCRIPTION
Classes istrstream, ostrstream, and strstream are specialization of
classes istream, ostream, and iostream, respectively, for I/O using in-
memory character arrays. That is, the associated streambuf is a
strstreambuf.
An auxiliary class strstreambase is an implementation detail, primarily
to provide a set of common functions. It is not further discussed.
istrstream members
istrstream(ptr)
Assumes ptr points to a null-terminated array of characters,
which will serve as the input source. The null is not part of
the input. Seeks, using seekg(), are allowed within the range
of the array.
istrstream(ptr, len)
Assumes ptr points to an array of characters of length len,
which will serve as the input source. Seeks, using seekg(), are
allowed within the range of the array.
strstreambuf* ssbp = iss.rdbuf()
Returns a pointer to the strstreambuf associated with iss. This
is the same as base class versions of this function, except that
the return type is specifically a strstreambuf*.
ostrstream members
ostrstream()
Creates an empty output stream, which uses a dynamic (expand‐
able) array of characters (see ssbuf(3CC4). Seeks are permitted
within the current bounds of the array. Presumably this stream
will be converted later to a char* via str() (see below).
ostrstream(ptr, len, mode)
Creates an output stream using the static (non-expandable) array
of len characters starting at ptr. If the ios::ate or ios::app
bits are set in mode (see ios(3CC4)), the array is assumed to
contain a null-terminated string beginning at ptr. Characters
will be stored beginning at the null character, but will never
go beyond len characters. If those bits are not set in mode,
the array is assumed to contain no data, and characters will be
stored beginning at ptr. Seeks are allowed within the range of
the array.
strstreambuf* ssbp = oss.rdbuf()
Returns a pointer to the strstreambuf associated with oss. This
is the same as base class versions of this function, except that
the return type is specifically a strstreambuf*.
int n = oss.pcount()
Returns the number of characters stored in the array. This is
of use particularly when the array contains binary data or is
not otherwise null-terminated.
char* ptr = oss.str()
Returns a pointer to the start of the underlying array, and
freezes (see strstreambuf(3C++)) the stream. If the array was
dynamically allocated, it will not now be automatically deleted
or null-terminated, and is no longer expandable (see freeze() in
strstreambuf). Until str() is called, a dynamically allocated
array would be automatically freed when the streambuf was
destroyed. Afterward, the user is responsible for the array and
when to free it.
strstream members
strstream()
Creates an empty bidirectional stream, which uses a dynamic
(expandable) array of characters (see ssbuf(3CC4). Seeks are
permitted within the current bounds of the array.
strstream(ptr, len, mode)
Creates a bidirectional stream using the static (non-expandable)
array of len characters starting at ptr. If the ios::ate or
ios::app bits are set in mode (see ios(3CC4)), the array is
assumed to contain a null-terminated string beginning at ptr.
Characters will be stored beginning at the null character, but
will never go beyond len characters. If those bits are not set
in mode, the array is assumed to contain no data, and characters
will be stored beginning at ptr. Seeks are allowed within the
range of the array.
strstreambuf* ssbp = ss.rdbuf()
Returns a pointer to the strstreambuf associated with ss. This
is the same as base class versions of this function, except that
the return type is specifically a strstreambuf*.
char* ptr = ss.str()
Returns a pointer to the start of the underlying array, and
freezes (see strstreambuf(3C++)) the stream. If the array was
dynamically allocated, it will not now be automatically deleted
or null-terminated, and is no longer expandable (see freeze() in
strstreambuf). Until str() is called, a dynamically allocated
array would be automatically freed when the streambuf was
destroyed. Afterward, the user is responsible for the array and
when to free it.
SEE ALSOios.intro(3CC4), ios(3CC4), istream(3CC4), ostream(3CC4), sbuf‐
pub(3CC4), ssbuf(3CC4),
C++ Library Reference
Chapter 3, "The Classic iostream Library."
14 March 1995 STRSTREAM(3CC4)
