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NAME
ostream - formatted and unformatted output
SYNOPSIS
#include <iostream.h>
typedef long streampos;
typedef long streamoff;
class unsafe_ios {
public:
// exported types
// stream operation mode
enum open_mode {
in = 0x01, // open for reading
out = 0x02, // open for writing
ate = 0x04, // seek to eof upon original open
app = 0x08, // append mode: all additions at eof
trunc = 0x10, // truncate file if already exists
nocreate = 0x20, // open fails if file doesn't exist
noreplace= 0x40 // open fails if file already exists
};
// stream seek direction
enum seek_dir { beg=0, cur=1, end=2 };
// formatting flags
enum {
skipws = 0x0001, // skip whitespace on input
left = 0x0002, // left-adjust output
right = 0x0004, // right-adjust output
internal = 0x0008, // padding after sign or base indicator
dec = 0x0010, // decimal conversion
oct = 0x0020, // octal conversion
hex = 0x0040, // hexidecimal conversion
showbase = 0x0080, // use base indicator on output
showpoint = 0x0100, // force decimal point (floating output)
uppercase = 0x0200, // upper-case hex output
showpos = 0x0400, // add '+' to positive integers
scientific= 0x0800, // use 1.2345E2 floating notation
fixed = 0x1000, // use 123.45 floating notation
unitbuf = 0x2000, // flush all streams after insertion
stdio = 0x4000 // flush stdout, stderr after insertion
};
// see ios(3C++) for remainder ...
};
class unsafe_ostream : virtual public unsafe_ios {
public:
// exported functions
// unformatted output functions
unsafe_ostream& put(char c);
unsafe_ostream& write(const char* ptr, int len);
// wide character
unsafe_ostream& put(wchar_t wc);
unsafe_ostream& write(const wchar_t * wptr, int len);
// other functions
int opfx();
void osfx();
unsafe_ostream& flush();
unsafe_ostream& seekp(streampos pos);
unsafe_ostream& seekp(streamoff offset, unsafe_ios::seek_dir from);
streampos tellp();
public:
// exported operator functions
unsafe_ostream& operator<< (char);
unsafe_ostream& operator<< (unsigned char);
unsafe_ostream& operator<< (short);
unsafe_ostream& operator<< (unsigned short);
unsafe_ostream& operator<< (int);
unsafe_ostream& operator<< (unsigned int);
unsafe_ostream& operator<< (long);
unsafe_ostream& operator<< (unsigned long);
unsafe_ostream& operator<< (float);
unsafe_ostream& operator<< (double);
unsafe_ostream& operator<< (const char* buf);
unsafe_ostream& operator<< (void* ptr);
unsafe_ostream& operator<< (streambuf* sbufp);
unsafe_ostream& operator<< (unsafe_ostream& (*manip)(unsafe_ostream&));
unsafe_ostream& operator<< (unsafe_ios& (*manip)(unsafe_ios&));
public:
// wide character
unsafe_ostream& operator<< (wchar_t);
unsafe_ostream& operator<< (const wchar_t*);
public:
// exported constructors
unsafe_ostream(streambuf* sbufp);
};
class ostream : virtual public ios, public unsafe_ostream {
public:
// unformatted output functions
ostream& put(char);
ostream& write(const char* ptr, int n);
ostream& write(const unsigned char* ptr, int n);
// wide character
ostream& put(wchar_t);
ostream& write(const wchar_t *, int);
// other functions
int opfx();
int osfx();
ostream& flush();
ostream& seekp(streampos);
ostream& seekp(streamoff, seek_dir);
streampos tellp();
public:
// exported operator functions
ostream& operator<<(char);
ostream& operator<<(unsigned char);
ostream& operator<<(short);
ostream& operator<<(unsigned short);
ostream& operator<<(int);
ostream& operator<<(unsigned int);
ostream& operator<<(long);
ostream& operator<<(unsigned long);
ostream& operator<<(float);
ostream& operator<<(double);
ostream& operator<<(const char*);
ostream& operator<<(void*);
ostream& operator<<(streambuf*);
ostream& operator<<(ostream& (*)(ostream&));
ostream& operator<<(ios& (*)(ios&));
public:
// wide character
ostream& operator<< (wchar_t);
ostream& operator<< (const wchar_t*);
public:
// exported constructor
ostream(streambuf* sbufp);
};
class ostream_withassign : public ostream {
public:
ostream_withassign();
ostream_withassign& operator= (ostream& ostr);
ostream_withassign& operator= (streambuf* sbufp);
};
extern ostream_withassign cout;
extern ostream_withassign cerr;
extern ostream_withassign clog;
ios& dec(ios&);
ios& hex(ios&);
ios& oct(ios&);
ostream& endl(ostream&);
ostream& ends(ostream&);
ostream& flush(ostream&);
unsafe_ios& dec(unsafe_ios&) ;
unsafe_ios& hex(unsafe_ios&) ;
unsafe_ios& oct(unsafe_ios&) ;
unsafe_ostream& endl(unsafe_ostream& i) ;
unsafe_ostream& ends(unsafe_ostream& i) ;
unsafe_ostream& flush(unsafe_ostream&) ;
DESCRIPTION
Class ostream supports formatted and unformatted insertion
(output) of data to an associated streambuf.
Class unsafe_ostream implements all of the functionality
described below, but does not prevent simultaneous access by
multiple threads; class ostream is a "wrapper" class that
implements mutex locks around each of the respective member
functions of unsafe_ostream to ensure mt-safety. Simply
using the mt-safe class does not guarantee mt-safe behaviour
by your application. For complete information on sharing of
iostream objects between cooperating threads, see the C++
4.1 Library Reference Manual, Chapter 5, "Using libC in a
Multithreaded Environment."
ENVIRONMENT
The discussion about thread safety applies only to Solaris
2.x. On Solaris 1.x the ``safe'' and ``unsafe'' functions
behave identically.
Constructors and Assignment
ostream(sbufp)
Associates the streambuf pointed to by sbufp with the
stream and initializes the ios state.
ostream_withassign()
Performs no initialization.
ostream_withassign osw = sbufp
Associates the streambuf pointed to by sbufp with osw
and completely initializes osw.
ostream_withassign osw = ostr
The streambuf associated with ostr becomes associated
with osw and the constructor completely initializes
osw.
Note:
local objects of class ostream_withassign must be ini-
tialized.
Wide character support
All operations that output wide characters to a stream set
ios::failbit and stop output if they encounter a wide char-
acter with no multibyte representation in the current
locale. They all call opfx().
Output prefix and suffix functions
int i = ostr.opfx()
Performs setup common to all insertion operations. If
the error state of ostr is non-zero, opfx returns zero
immediately. If a stream is tied to ostr (see tie in
ios(3C++)), the tied stream is flushed. Function opfx
returns zero if any error condition is encountered,
non-zero otherwise. User-defined inserters should
start by calling opfx.
ostr.osfx()
Performs followup actions at the conclusion of an
insertion operation. If ios::unitbuf is set, flushes
the stream. If ios::stdio is set, flushes stdout and
stderr. (See ios(3C++).) It has no return value. All
predefined inserters call osfx, but the unformatted
output functions do not. User-defined inserters should
call osfx before returning.
Formatted output (insertion) functions
The formatted output functions call opfx(). If it returns
zero, no further action takes place. The functions also
call osfx() before returning (if opfx() succeeded).
ostr << sbufp
If ostr.opfx() returns non-zero, inserts all the char-
acters into ostr that that can be extracted from the
streambuf pointed to by sbufp. No padding is per-
formed. Returns a reference to ostr. You can use this
function to copy a stream efficiently, but you should
be sure that neither stream is tied. For example:
#include <iostream.h>
main()
{ // copy cin to cout
cin.tie(0);
cout.tie(0);
cout << cin.rdbuf(); // see ios(3C++) for rdbuf
return 0;
}
ostr << x
If ostr.opfx(0) returns non-zero, inserts characters
representing x into ostr. If opfx returns zero, no
action is taken. Any errors encountered are recorded
in the error state of ostr. These functions always
return a reference to ostr. User-written functions
should be of the form
ostream& operator<< (ostream&, SomeType)
and should conform to these principles.
The type of x and the format state of the ostream (see
ios(3C++) determine the details of the conversion and
insertion. These functions do not change the state of
the ostream, except that the width variable is reset to
zero after each formatted insertion. The predefined
formatted inserters and their conversion rules are as
follows:
char, unsigned char, signed char
Inserts the character x into ostr without conversion.
wchar_t
Converts the wide character to multibyte representation
and inserts onto the stream. Sets ios::failbit and
stops if the wide character has no multibyte represen-
tation in the current locale.
short, unsigned short
int, unsigned int
long, unsigned long
The representation consists of a sequence of ``digits''
with no leading zeros. The digits and coversion are
octal if ios::oct is set, hexadecimal if ios::hex is
set, decimal if ios::dec or none of these is set. For
decimal conversion, if x is positive and ios::showpos
is set, there is a leading plus sign (`+'); if x is
negative there is a leading minus sign (`-'). The
octal and hexadecimal conversions are treated as
unsigned; no sign is included. If ios::showbase is
set, there is a leading `0' for octal conversion and a
leading ``0x'' or ``0X'' for hexadecimal conversion,
depending on whether ios::uppercase is set.
float, double
The value of x is converted according to the current
values in ostr of precision, width, ios::scientific,
ios::fixed, and ios::uppercase. See ios(3C++).
char*
The representation is the sequence of characters
pointed to by x up to but not including the first null
(0) character.
wchar_t*
Inserts the multibyte representation of the wide char-
acters in the array up to the first 0 wide character.
Sets ios::failbit and stops if it encounters a wide
character with no multibyte representation in the
current locale. Note that padding is based on a field
width measured in characters rather than bytes. In the
current implementation, the fill character is always a
single byte.
void*
The pointer is converted as if it were an int and
ios::showbase and ios::hex were set.
Unformatted output (insertion) functions
These operations do not call opfx() or osfx().
ostr.put(c)
Inserts the character c into ostr. Sets the error
state if the operation fails. Always returns a
reference to ostr.
ostr.put(wc)
Puts the multibyte representation of the wide character
into ostr. Sets the error state if the operation
fails. Always returns a reference to ostr.
ostr.write(ptr, len)
Inserts exactly len characters starting the beginning
of the char array pointed to by ptr into ostr. Sets
the error state if the operation fails. Always returns
a reference to ostr.
ostr.write(wptr, len)
Puts out the multibyte representations of exactly count
wide characters pointed to by wptr into ostr.
Positioning functions
These deal with the put pointer of the streambuf associated
with an ostream. See sbufpub(3C++) for a complete discus-
sion. Multibyte input operations may cause the get pointer
of the streambuf to differ from the value reported by
tellg(), but seeks done on the istream rather than the
streambuf will still coordinate correctly with all opera-
tions on the istream.
ostr.seekp(pos)
ostr.seekp(off, dir)
These set the position of the put pointer; they return
a reference to ostr.
streampos pos = ostr.tellp()
This returns the current position of the put pointer.
Miscellaneous functions
ostr.flush()
This causes any characters stored into the associated
streambuf to be flushed; for example, written to the
output file. It returns a reference to ostr.
Predefined Manipulators
A manipulator may be used apparently as an inserted or
extracted object, but many only change the state of the
stream. See manip(3C++) and ios(3C++) for more information.
Several manipulators are predefined for use with ostreams.
ostr << manip
This is equivalent to the call manip(ostr).
ostr << dec
This sets the conversion base of ostr to 10.
ostr << oct
This sets the conversion base of ostr to 8.
ostr << hex
This sets the conversion base of ostr to 16.
ostr << endl
This ends a line by inserting a newline and flushing
ostr.
ostr << ends
This ends a string by inserting null (0) character into
ostr.
ostr << flush
This is equivalent to calling ostr.flush().
SEE ALSO
ios.intro(3C++), ios(3C++), manip(3C++), sbufpub(3C++),
C++ 4.1 Library Reference Manual:
Chapter 4, "The Iostream Library",
Chapter 5, "Using libC in a Multithreaded Environment."
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