C++ Stream Library

strstream(C++)

strstream -- iostream specialized to arrays

Syntax

#include <strstream.h>

class ios {
public:
	enum	open_mode { in, out, ate, app, trunc, nocreate, noreplace };
	// and lots of other stuff, see ios(C++) ...
} ;

class strstreambase : public virtual ios {
       ...
} ;

class istrstream : public istream {
public:
			istrstream(char*) ;
			istrstream(char*, int) ;
	strstreambuf*	rdbuf() ;
} ;

class ostrstream : public ostream {
public:
			ostrstream();
			ostrstream(char*, int, int=ios::out) ;
	int		pcount() ;
	strstreambuf*	rdbuf() ;
	char*		str();
};

class strstream : public strstreambase, public iostream {
public:
			strstream();
			strstream(char*, int, int mode);
	strstreambuf*	rdbuf() ;
	char*		str();
};

Description

strstream specializes iostream for ``incore'' operations, that is, storing and fetching from arrays of bytes. The streambuf associated with a strstream is a strstreambuf (see ssbuf(C++)).

In the following descriptions assume:

ss is a strstream
iss is an istrstream
oss is an ostrstream
cp is a char*
mode is an int representing an open_mode
i and len are ints
ssb is a strstreambuf*

Constructors

istrstream(cp): Characters will be fetched from the (null-terminated) string cp. The terminating null character will not be part of the sequence. Seeks (istream::seekg()) are allowed within that space.
istrstream(cp, len): Characters will be fetched from the array beginning at cp and extending for len bytes. Seeks (istream::seekg()) are allowed anywhere within that array.
ostrstream(): Space will be dynamically allocated to hold stored characters.
ostrstream(cp,n,mode): Characters will be stored into the array starting at cp and continuing for n bytes. If ios::ate or ios::app is set in mode, cp is assumed to be a null-terminated string and storing will begin at the null character. Otherwise storing will begin at cp. Seeks are allowed anywhere in the array.
strstream(): Space will be dynamically allocated to hold stored characters.
strstream(cp,n,mode): Characters will be stored into the array starting at cp and continuing for n bytes. If ios::ate or ios::app is set in mode, cp is assumed to be a null-terminated string and storing will begin at the null character. Otherwise storing will begin at cp. Seeks are allowed anywhere in the array. Note that, if mode is set to ios::in|ios::out, the original string (if any) stored at cp will not be accessible unless seeks (ostream::seekp()) are used to adjust the put pointer.

istrstream members

ssb=iss.rdbuf(): Returns the strstreambuf associated with iss.

ostrstream members

ssb=oss.rdbuf(): Returns the strstreambuf associated with oss.
cp=oss.str(): Returns a pointer to the array being used and ``freezes'' the array. Once str has been called the effect of storing more characters into oss is undefined. If oss was constructed with an explicit array, cp is just a pointer to the array. Otherwise, cp points to a dynamically allocated area. Until str is called, deleting the dynamically allocated area is the responsibility of oss. After str returns, the array becomes the responsibility of the user program.
i=oss.pcount(): Returns the number of bytes that have been stored into the buffer. This is mainly of use when binary data has been stored and oss.str() does not point to a null terminated string.

strstream members

ssb=ss.rdbuf(): Returns the strstreambuf associated with ss.
cp=ss.str(): Returns a pointer to the array being used and ``freezes'' the array. Once str has been called the effect of storing more characters into ss is undefined. If ss was constructed with an explicit array, cp is just a pointer to the array. Otherwise, cp points to a dynamically allocated area. Until str is called, deleting the dynamically allocated area is the responsibility of ss. After str returns, the array becomes the responsibility of the user program.