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Annotation of researchv10dc/man/mana/ios.3, revision 1.1

1.1     ! root        1: .  \"ident     "%W%"
        !             2: .  \"Copyright (c) 1984 AT&T
        !             3: .  \"All Rights Reserved
        !             4: .  \"THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T
        !             5: .  \"The copyright notice above does not evidence any
        !             6: .  \"actual or intended publication of such source code.
        !             7: .TH IOSTREAM 3I+ "C++ Stream Library" " "
        !             8: .SH NAME
        !             9: ios \- input/output formatting
        !            10: .SH SYNOPSIS
        !            11: .nf
        !            12: .ta1i 2i
        !            13: .ft B
        !            14: #include <iostream.h>
        !            15: 
        !            16: struct fmtinfo {
        !            17:        ostream*        tie;
        !            18:        short   convbase;
        !            19:        short   width;
        !            20:        short   precision;
        !            21:        char    fill;
        !            22:        char    ladjust;
        !            23:        char    showbase;
        !            24:        char    skip;
        !            25:        char    floatfmt;
        !            26: };
        !            27: 
        !            28: class ios {
        !            29: public:
        !            30:        enum    io_state { goodbit=0, eofbit, failbit, badbit };
        !            31:        enum    open_mode { in, out, ate, app };
        !            32:        enum    seek_dir { beg, cur, end };
        !            33: public:
        !            34:                ios(streambuf* b);
        !            35: 
        !            36:        int     bad();
        !            37:        void    clear(state_value i = _good);
        !            38:        int     convbase();
        !            39:        void    convbase(int i);
        !            40:        int     eof();
        !            41:        int     fail();
        !            42:        char    fill();
        !            43:        void    fill(char c);
        !            44:        char    floatfmt();
        !            45:        void    floatfmt(char c);
        !            46:        fmtinfo fmt();
        !            47:        void    fmt(fmtinfo& info);
        !            48:        int     ladjust();
        !            49:        void    ladjust(int a);
        !            50:        int     good();
        !            51:        int     operator!();
        !            52:                operator int();
        !            53:        int     popfmt();
        !            54:        int     precision();
        !            55:        void    precision(int i);
        !            56:        void    pushfmt();
        !            57:        streambuf*      rdbuf();
        !            58:        int     rdstate();
        !            59:        int     showbase();
        !            60:        void    showbase(int i);
        !            61:        int     skip();
        !            62:        int     skip(int i);
        !            63:        void    sync_with_stdio();
        !            64:        streampos       tellg();
        !            65:        ostream*        tie();
        !            66:        ostream*        tie(ostream* iosp);
        !            67:        int     width();
        !            68:        void    width(int i);
        !            69: 
        !            70:        ios&    operator<<(ios& (*)(ios&));
        !            71:        ios&    operator>>(ios& (*)(ios&));
        !            72: private:
        !            73:                iostream(iostream&) ;
        !            74:        iostream&       operator=(iostream&)    ;
        !            75: };
        !            76: 
        !            77: class ios_withassign : ios {
        !            78:                ios_withassign();
        !            79:        ios&    operator=(ios&);
        !            80:        ios&    operator=(streambuf*);
        !            81: } ;
        !            82: 
        !            83: ios&   dec(ios& i) ; 
        !            84: ios&   hex(ios& i) ;
        !            85: ios&   oct(ios& i) ;
        !            86: ios&   popfmt(ios& i) ;
        !            87: ios&   pushfmt(ios& i) ;
        !            88: .fi
        !            89: .ft R
        !            90: .SH DESCRIPTION
        !            91: The stream classes derived from \f(CWios\fRs
        !            92: provide a high level interface that
        !            93: supports transferring
        !            94: formatted and unformatted information into and out of
        !            95: \f(CWstreambuf\fRs.
        !            96: .PP
        !            97: In the following assume:
        !            98: .br
        !            99: \(em \fBs\fR is an \f(CWios\fR.
        !           100: .br
        !           101: \(em \fBswa\fR is an \f(CWios_withassign\fR.
        !           102: .br
        !           103: \(em \fBsp\fR is a \f(CWios*\fR.
        !           104: .br
        !           105: \(em \fBi\fR and \fBn\fR are \f(CWint\fR.
        !           106: .br
        !           107: \(em \fBc\fR is a \f(CWchar\fR.
        !           108: .br
        !           109: \(em \fBosp\fR is an \f(CWostream*\fR.
        !           110: .br
        !           111: \(em \fBsb\fR is a \f(CWstreambuf*\fR.
        !           112: .br
        !           113: \(em \fBpos\fR is a \f(CWstreampos\fR.
        !           114: .br
        !           115: \(em \fBoff\fR is a \f(CWstreamoff\fR.
        !           116: .br
        !           117: \(em \fBinfo\fR is a \f(CWformatinfo\fR.
        !           118: .br
        !           119: \(em \fBdir\fR is a \f(CWseek_dir\fR.
        !           120: .br
        !           121: \(em \fBmode\fR is a \f(CWseek_dir\fR.
        !           122: .br
        !           123: \(em \fBfct\fR is a function with type \f(CWios& (*)(ios&)\fR.
        !           124: .PP
        !           125: Constructors and assignment:
        !           126: .TP
        !           127: \fBios(sb)\fR
        !           128: \fBsb\fR becomes the \f(CWstreambuf\fR associated with the
        !           129: constructed \fBios\fR.  This association is fixed for
        !           130: the life of the \f(CWios\fR. If \fBsb\fR is null the effect is
        !           131: undefined.
        !           132: .TP
        !           133: \fBios_withassign()\fR
        !           134: Uninitialized variable.
        !           135: .sp
        !           136: .nf
        !           137: .in -.5i
        !           138: \fBios(ios&)\fR
        !           139: \fBios=ios\fR
        !           140: .in
        !           141: .fi
        !           142: Copying of \f(CWios\fR's is not in general
        !           143: well defined and the constructor and assignment operators
        !           144: are made private so that the compiler will complain about attempts to
        !           145: do so.  Usually what is desired
        !           146: is copying of pointers to \f(CWiostream\fRs.
        !           147: .TP
        !           148: swa=sb
        !           149: Associates \fBsb\fR with \fBswa\fR and initializes the entire
        !           150: state of
        !           151: \fBswa\fR. 
        !           152: .TP
        !           153: swa=s
        !           154: Associates \fBs->rdbuf()\fR with \fBswa\fR and
        !           155: initializes the entire state of
        !           156: \fBswa\fR. 
        !           157: .PP
        !           158: An \fBios\fR has an internal error state (which is a collection
        !           159: of the bits declared as \f(CWio_state\fRs).  Members related
        !           160: to the error state:
        !           161: .RS
        !           162: .TP
        !           163: \fBi=s.rdstate()\fR
        !           164: Returns the current error state.
        !           165: .TP
        !           166: \fBs.clear(i)\fR
        !           167: Stores \fBi\fR as the error state.  If \fBi\fR is zero
        !           168: this clears all bits.  To set a bit without clearing previously
        !           169: set bits requires something like \fBs.clear(badbit|s.rdstate())\fR.
        !           170: .TP
        !           171: \fBi=s\fR
        !           172: The \f(CWint\fR conversion operator is non-zero if \f(CWbadbit\fR or
        !           173: \f(CWfailbit\fR is set in the error state.
        !           174: .TP
        !           175: \fBi=s.good()\fR
        !           176: Non-zero if the error state has no bits set.
        !           177: .TP
        !           178: \fBi=s.eof()\fR
        !           179: Non-zero if \f(CWeofbit\fR is set in the error state.  Normally this
        !           180: bit is set when an end of file has been encountered doing extraction.
        !           181: .TP
        !           182: \fBi=s.fail()\fR
        !           183: Non-zero if either \f(CWbadbit\fR or \f(CWfailbit\fR are set in the
        !           184: error state.  Normally this indicates that some operation has failed.
        !           185: .TP
        !           186: \fBi=s.bad()\fR
        !           187: Non-zero if \fBbadbit\fR is set in the error state.
        !           188: Normally this indicates
        !           189: that some operation on \fBs.rdbuf()\fR has failed.
        !           190: .RE
        !           191: .PP
        !           192: An \f(CWios\fR has a collection of format state variables
        !           193: that are used by input and output operations to control the
        !           194: details of formatting operations.  Otherwise their values
        !           195: have no particular effect and they may be set and examined arbitrarily
        !           196: by user code.
        !           197: .RS
        !           198: .TP
        !           199: \fBs.convbase(i)\fR
        !           200: Sets the "conversion base" format state variable to \fBi\fR.
        !           201: .TP
        !           202: \fBi=s.convbase()\fR
        !           203: Returns the "conversion base" format state variable.
        !           204: .TP
        !           205: \fBs.fill(c)\fR
        !           206: Sets the "fill character" format state variable to \fBc\fR.
        !           207: .TP
        !           208: \fBc=s.fill()\fR
        !           209: Returns the "fill character" format state variable.
        !           210: .TP
        !           211: \fBs.fill(c)\fR
        !           212: Sets the "fill character" format state variable to \fBc\fR.
        !           213: .TP
        !           214: \fBc=s.fill()\fR
        !           215: Returns the "fill character" format state variable.
        !           216: .TP
        !           217: \fBs.floatfmt(c)\fR
        !           218: Sets the "floating format" format state variable to \fBc\fR.
        !           219: .TP
        !           220: \fBc=s.floatfmt()\fR
        !           221: Returns the "floating format" format state variable.
        !           222: .TP
        !           223: \fBs.ladjust(i)\fR
        !           224: Sets the "left adjustment" format state variable to \fBi\fR.
        !           225: .TP
        !           226: \fBi=s.ladjust()\fR
        !           227: Returns the "left adjustment" format state variable.
        !           228: .TP
        !           229: \fBs.precision(i)\fR
        !           230: Sets the "precision" format state variable to \fBi\fR.
        !           231: .TP
        !           232: \fBi=s.precision()\fR
        !           233: Returns the "precision" format state variable.
        !           234: .TP
        !           235: \fBs.showbase(i)\fR
        !           236: Sets the "show explicit base" format state variable to \fBi\fR.
        !           237: .TP
        !           238: \fBi=s.showbase()\fR
        !           239: Returns the "show explicit base" format state variable.
        !           240: .TP
        !           241: \fBsp=s.skip(sp)\fR
        !           242: Sets the "skip whitespace" format state variable to \fBsp\fP.
        !           243: .TP
        !           244: \fBsp=s.skip()\fR
        !           245: Returns the "skip whitespace" format state variable.
        !           246: .TP
        !           247: \fBosp=s.tie(osp)\fR
        !           248: Sets the "tie" format state variable \fBsp\fP.
        !           249: .TP
        !           250: \fBosp=s.tie()\fR
        !           251: Returns the "tie" format state variable.
        !           252: .TP
        !           253: \fBs.width(i)\fR
        !           254: Sets the "field width" format state variable to \fBi\fP.
        !           255: .TP
        !           256: \fBi=s.width()\fR
        !           257: Returns the "field width" format state variable.
        !           258: .TP
        !           259: \fBs.fmt(info)\fR
        !           260: Sets the collection of all format state variables to \fBinfo\fP in
        !           261: a single operation.
        !           262: .TP
        !           263: \fBinfo=s.fmt()\fR
        !           264: Returns the collection of all format state variables in
        !           265: a single operation.
        !           266: .TP
        !           267: \fBs.pushfmt()\fR
        !           268: Pushes a \f(CWformatinfo\fR structure onto a (dynamically allocated)
        !           269: stack associated with \fBs\fR.  This copies the current
        !           270: values of format state variables without changing them.
        !           271: .TP
        !           272: \fBi=s.popfmt()\fR
        !           273: Pops the topmost \f(CWformatinfo\fR from the stack associated with
        !           274: \fBs\fR and sets the format state variables accordingly.  Normally
        !           275: \fBi\fR is non-zero, but it will be zero if the stack is empty
        !           276: (i.e., more \fBpopfmt\fR than \fBpushfmt\fR operations have been
        !           277: performed.
        !           278: .RE
        !           279: .PP
        !           280: Other members:
        !           281: .TP
        !           282: \fBsb=s.rdbuf()\fR
        !           283: Returns a pointer to the \f(CWstreambuf\fR associated with
        !           284: \fBs\fR when \fBs\fR was constructed.
        !           285: .TP
        !           286: \fB((ios*)0)->sync_with_stdio()\fR
        !           287: Solves problems that arise when mixing stdio and
        !           288: iostreams.   The first time it is called it will reset the
        !           289: standard iostreams (\f(CWinstream\fR, \f(CWoutstream\fR, \f(CWerrstream\fR,
        !           290: \f(CWlogstream\fR) to be streams
        !           291: using  \f(CWstdiobuf\fRs.
        !           292: After that input and output using these streams may
        !           293: be mixed with input and output using the corresponding \f(CWFILE\fRs and
        !           294: will be properly synchronized.
        !           295: .RE
        !           296: .PP
        !           297: Convenient manipulators (functions that take an \f(CWios&\fR
        !           298: and return their argument).
        !           299: .TP
        !           300: \fBios<<dec
        !           301: .in -.5i
        !           302: .br
        !           303: .nf
        !           304: \fBios<<dec
        !           305: \fBios>>dec\fR
        !           306: .fi
        !           307: .in
        !           308: Sets the convbase to 10.
        !           309: .sp
        !           310: .nf
        !           311: .in -.5i
        !           312: \fBios<<hex
        !           313: \fBios>>hex\fR
        !           314: .in
        !           315: Sets the convbase to 16.
        !           316: .sp
        !           317: .nf
        !           318: .in -.5i
        !           319: \fBios<<oct
        !           320: \fBios>>oct\fR
        !           321: .fi
        !           322: .in
        !           323: Sets the convbase to 8.
        !           324: .sp
        !           325: .nf
        !           326: .in -.5i
        !           327: \fBios<<popfmt
        !           328: \fBios>>popfmt\fR
        !           329: .fi
        !           330: .in
        !           331: Does \fBs.popfmt()\fR
        !           332: .in -.5i
        !           333: .sp
        !           334: .nf
        !           335: \fBios<<pushfmt
        !           336: \fBios>>pushfmt\fR
        !           337: .fi
        !           338: .in
        !           339: Does \fBs.pushfmt()\fR
        !           340: .PP
        !           341: The \f(CWstreambuf\fR associated with an \f(CWios\fR may be manipulated
        !           342: by other methods than through \f(CWios\fR.  For example, characters may
        !           343: be stored in a queuelike \f(CWstreambuf\fR through an \f(CWostream\fR
        !           344: while they are being fetched through an \f(CWistream\fR.
        !           345: Or for efficiency some
        !           346: part of a program may choose to do \f(CWstreambuf\fR gets
        !           347: directly rather than through the \f(CWios\fR.
        !           348: In most cases
        !           349: the program does not have to worry about this possibility, because
        !           350: an \f(CWios\fR never saves information about the internal state
        !           351: of a \f(CWstreambuf\fR.  For example if the \f(CWstreambuf\fR is
        !           352: repostitioned between extraction operations the extraction (input) 
        !           353: will proceed normally.
        !           354: .SH CAVEATS
        !           355: .PP
        !           356: The effect of \fBios.sync_with_stdio()\fR
        !           357: does not depend on \fBios\fR.
        !           358: \fBsync_with_stdio\fR ought
        !           359: to be a global function but it is a member of \fBiostream\fR to
        !           360: avoid name space pollution.
        !           361: The need for \fBsync_with_stdio\fR is a wart.  The old stream
        !           362: package did this as a default, but in the iostream package
        !           363: unbuffered \f(CWstdiobuf\fRs are too inefficient to be the default.
        !           364: .PP
        !           365: The stream package had a constructor that took a \fBFILE*\fR argument.
        !           366: This is now replaced by \f(CWstdiostream\fR.
        !           367: It is not declared even as an obsolete form to avoid
        !           368: having \f(CWiostream.h\fR
        !           369: depend on \f(CWstdio.h\fR.
        !           370: .PP
        !           371: The old stream package allowed copying of streams.  This is disallowed
        !           372: by the iostream package.  Old code using copying can usually be
        !           373: rewritten to use pointers and copy pointers.
        !           374: .PP
        !           375: For compatibility with the old stream package, the versions of 
        !           376: .I tie
        !           377: and
        !           378: .I skip
        !           379: that set the state variables also return the old value.
        !           380: .SH SEE ALSO
        !           381: IOS.INTRO(3C++)
        !           382: streambuf(3C++)
        !           383: istream(3C++)
        !           384: ostream(3C++)

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