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把pascal程序转成C语言程序 把pascal程序转成C语言程序

                         ReplaceBefore "{$ifdef" "{EMBED  #ifdef"
                         ReplaceBefore     "{$endif}"     "{EMBED
                    #endif}"

                    These lines rewrite Turbo Pascal compile-time
                    conditionals into comments beginning with the
                    special word EMBED.  This word instructs  p2c
                    to format the rest of the comment without "/*
                    */" delimiters, i.e., the rest of the comment
                    is embedded directly in the output C program.
                    There is also a  ReplaceAfter  option,  which
                    specifies replacements to be done on the out-
                    put of _p_2_c.

                    Currently, this feature  makes  only  literal
                    string    replacements,   not   pattern-based
                    matches.  Some users of  _p_2_c  have  found  it
                    useful  to feed their Pascal programs through
                    a more  powerful  editor  like  _s_e_d  or  _p_e_r_l
                    before  giving  them to _p_2_c. Quite often this
                    is all that is necessary to get an acceptable
                    translation  in the face of unrecognized Pas-
                    cal dialects or language features.

     IncludeFrom    This specifies that a given  module's  header
                    should  be  included from a given place.  The
                    second argument may be surrounded by  " "  or
                    < >  as  necessary; if the second argument is
                    omitted, no include directive  will  be  gen-
                    erated for the module.

     ImportFrom     This specifies that a given  module's  Pascal
                    interface  text  can  be  found  in the given
                    file.  The named file should  be  either  the
                    source  file  for  the module, or a specially
                    prepared file with the implementation section
                    removed for speed.  If no ImportFrom entry is
                    found for a module, the path defined  by  the
                    ImportDir  list  is  searched.  Each entry in
                    the path may contain a %_s, which  expands  to
                    the  name  of  the  module.  The default path



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                    looks for %_s._p_a_s and %_s._t_e_x_t in  the  current
                    directory,   then   for  /_u_s_r/_l_i_b/_p_2_c/%_s._i_m_p.
                    (where /usr/lib/p2c is the  _p_2_c  home  direc-
                    tory.)

     StructFunction This parameter is a list of  functions  which
                    follow the _p_2_c semantics for structure-valued
                    functions (functions returning arrays,  sets,
                    and  strings,  and  structs  in  primitive  C
                    dialects).  For these functions, a pointer to
                    a return-value area is passed to the function
                    as a special first parameter.   The  function
                    stores  the result in this area, then returns
                    a copy of the pointer.  (The standard C func-
                    tion  _s_t_r_c_p_y  is  an example of this concept.
                    _S_p_r_i_n_t_f  also  behaves  this  way   in   some
                    dialects;    it   always   appears   on   the
                    StructFunction list regardless of the type of
                    implementation.)   The  system  configuration
                    file includes a  list  of  common  structured
                    functions  so  that _p_2_c's optimizer will know
                    how to manipulate them.

     StrlapFunction Functions on this list are  structured  func-
                    tions  as above, but with the ability to work
                    in-place; that is, the same  pointer  may  be
                    passed  as  both  the return value area and a
                    regular parameter.

     Deterministic  Functions on this list have no  side  effects
                    or  side dependencies.  An example is the _s_i_n
                    function in the standard  math  library;  two
                    calls  with the same parameter values produce
                    the same result, and have  no  effects  other
                    than  returning a value.  _P_2_c can make use of
                    this knowledge when optimizing code for effi-
                    ciency  or  readability.   Functions  on this
                    list are also assumed to be relatively  fast,
                    so  that it is acceptable to duplicate a call
                    to the function.

     LeaveAlone     Functions on this list are not  subjected  to
                    the  normal  built-in  translation rules that
                    _p_2_c would otherwise use.  For example, adding
                    _w_r_i_t_e_l_n  to this list would translate _w_r_i_t_e_l_n
                    statements blindly into calls  to  a  C  _w_r_i_-
                    _t_e_l_n() function, rather than being translated
                    into equivalent _p_r_i_n_t_f calls.   The  built-in
                    translation  is  also suppressed if the func-
                    tion has a FuncMacro.

     BufferedFile   _P_2_c normally assumes binary  files  will  use



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                    _r_e_a_d/_w_r_i_t_e,  not  _g_e_t/_p_u_t/^ notation.  A file
                    buffer variable will only be  created  for  a
                    file  if buffer notation is used for it.  For
                    global file variables this  may  be  detected
                    too  late  (a declaration without buffers may
                    already have been written).  Such  files  can
                    be  listed  in  BufferedFile  to force _p_2_c to
                    allocate buffers for them; do this if you get
                    a  warning message that says it is necessary.
                    Set BufferedFile=1 to buffer  all  files,  in
                    which case UnBufferedFile allows you to force
                    certain files _n_o_t to have buffers.

     StructFiles    If _p_2_c still can't translate your file opera-
                    tions correctly, you can set StructFiles=1 to
                    cause Pascal files to translate into  structs
                    which  include  the  usual C _F_I_L_E pointer, as
                    well as file buffer  and  file  name  fields.
                    While the resulting code doesn't look as much
                    like native C, the file  structs  will  allow
                    _p_2_c  to do a correct translation in many more
                    cases.

     CheckFileEOF   Normally  only   file-open   operations   are
                    checked  for errors.  Additional error check-
                    ing, such as  read-past-end-of-file,  can  be
                    enabled  with  parameters  like CheckFileEOF.
                    These checks can make the code very ugly!  If
                    I/O   checking  is  enabled  by  the  program
                    ($iocheck on$ in HP Pascal; {$I+}  in  Turbo;
                    this  is  always  the  default  state), these
                    checks  will  generate  fatal  errors  unless
                    enclosed  in  an  HP  Pascal try-recover con-
                    struct.  If I/O checking is  disabled,  these
                    will  cause the global variable _P__i_o_r_e_s_u_l_t to
                    be set zero or nonzero according to the  out-
                    come.   The default for most of these options
                    is  to  check  only  when  I/O  checking   is
                    enabled.

ISSUES
     Integer size. _P_2_c  normally  generates  code  to  work  with
     either  16 or 32 bit ints.  If you know your C integers will
     be 16 or 32 bits, set IntSize appropriately.  In  particular
     setting  IntSize=32  will generate much cleaner code: _p_2_c no
     longer must carefully cast function  arguments  between  int
     and long.  These casts also will be unnecessary if ANSI pro-
     totypes are available.  To disable int/long casting  because
     you  know  at  least one of these cases will hold, set Cast-
     LongArgs=0.   (The  CastArgs  parameter  similarly  controls
     other types of casts, such as between ints and doubles.) The
     Integer16 parameter controls  whether  Pascal  integers  are



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     interpreted  as  16  or  32  bits, or translated as native C
     integers.   The  default  value  depends  on  the   Language
     selected.

     Signed/unsigned  chars.  Pascal  characters   are   normally
     "weakly"  interpreted  as  unsigned;  this  is controlled by
     UnsignedChar.  The default is "either," so that  C's  native
     char  type  may  be used even if its signed-ness is unknown.
     Code that uses characters outside of  the  range  0-127  may
     need  a  different  setting.  Alternatively, you can use the
     types {SIGNED} char and {UNSIGNED} char  in  the  few  cases
     where  it  really matters.  These comments are controlled by
     the SignedComment and UnsignedComment parameters.  (The type
     {UNSIGNED}  integer  is  also  recognized.)   The SignedChar
     parameter tells whether C characters are signed or  unsigned
     (default  is  "unknown").  The HasSignedChar parameter tells
     whether the phrase "signed char" is legal in the output.  If
     it  is  not,  _p_2_c  may have to translate Pascal signed bytes
     into C shorts.

     Special types. _P_2_c understands the following predefined Pas-
     cal  type  names:  integer,  signed  integers  depending  on
     Integer16;  longint,  signed  32-bit   integers;   unsigned,
     unsigned  32-bit  integers;  sword,  signed 16-bit integers;
     word, unsigned  16-bit  integers;  c_int,  signed  native  C
     integers;  c_uint, unsigned native C integers; sbyte, signed
     8-bit  integers;  byte,  unsigned  8-bit   integers;   real,
     floating-point  numbers  depending  on  DoubleReals; single,
     single-precision floats;  longreal,  double,  and  extended,
     double-precision   floats;   pointer   and  anyptr,  generic
     pointers  (assignment-compatible  with  any  pointer  type);
     string,  generic  string  of  length StringDefault (normally
     255); also, the usual Pascal types char, boolean, and  text.
     (If your Pascal uses different names for these concepts, the
     Synonym option will come in handy.)

     Embedded code. It is possible to write a Pascal comment con-
     taining  C  code  to  be  embedded into the output.  See the
     descriptions of EmbedComment and its relatives in the system
     _p_2_c_r_c  file.  These techniques are helpful if you plan to do
     repeated translations of code that is still being maintained
     in  Pascal.   See  the  description  of ReplaceBefore for an
     example use of embedded code.

     Comments and blank lines. _P_2_c collects  the  comments  in  a
     procedure  into  a  list.   All  comments and statements are
     stamped with serial numbers which are used to reattach  com-
     ments to statements even after code has been added, removed,
     or  rearranged  during   translation.    "Orphan"   comments
     attached  to  statements that have been lost are attached to
     nearby statements or emitted at the end  of  the  procedure.
     Blank  lines  are  treated as a kind of comment, so _p_2_c will



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     also reproduce your usage of blank lines.   If  the  comment
     mechanism  goes  awry, you can disable comments with EatCom-
     ments or disable their being attached to code with  SpitCom-
     ments.

     Indentation. _P_2_c has a number of parameters to govern inden-
     tation  of  code.   The default values produce the GNU Emacs
     standard indentation style, although _p_2_c can do a better job
     since  it knows more about the code it is indenting.  Inden-
     tation works by applying  "indentation  deltas,"  which  are
     either  absolute numbers (which override the previous inden-
     tation), or signed relative numbers (which augment the  pre-
     vious  indentation).  A delta of "+0" specifies no change in
     indentation.  All of the indentation options  are  described
     in the standard _p_2_c_r_c file.

     Line breaking. _P_2_c uses an  algorithm  similar  to  the  TeX
     typesetter's  paragraph  formatter  for breaking long state-
     ments into multiple lines.  A "penalty" is assigned to vari-
     ous  undesirable  aspects  of  all possible line breaks; the
     "badness" of a set of line breaks is approximately  the  sum
     of  all the penalties.  Chief among these are serious penal-
     ties  for  overrunning  the  desired  maximum  line   length
     (default  78  columns),  an infinite penalty for overrunning
     the absolute maximum line length (default 90), and  progres-
     sively  greater  penalties  for breaking at operators deeply
     nested in expressions.  Parameters  such  as  OpBreakPenalty
     control the relative weights of various choices.  BreakArith
     and its neighbors control whether the  opera