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       ctangle, cweave – translate CWEB to TeX


       ctangle [options] webfile[.w] [{changefile[.ch]|-} [outfile[.c]]]
       cweave [options] webfile[.w] [{changefile[.ch]|-} [outfile[.tex]]]


       The  ctangle  program  converts  a  CWEB  source document into a C/C++ program that may be
       compiled in the usual  way.   The  output  file  includes  #line  specifications  so  that
       debugging can be done in terms of the CWEB source file.

       The  cweave  program converts the same CWEB file into a TeX file that may be formatted and
       printed in the usual way.  It takes appropriate care  of  typographic  details  like  page
       layout  and  the  use  of  indentation, italics, boldface, etc., and it supplies extensive
       cross-index information that it gathers automatically.

       CWEB allows you to prepare a single document containing all the information that is needed
       both  to  produce  a  compilable  C/C++ program  and  to produce a well-formatted document
       describing the program in as much detail as the writer may desire.  The user of CWEB ought
       to be familiar with TeX as well as C/C++.


       The  command  line  should have one, two, or three names on it.  The first is taken as the
       CWEB input file (and .w is added if there is no extension).  If there is a second name, it
       is  a  change file (and .ch is added if there is no extension).  The change file overrides
       parts of the CWEB file, as described in the documentation.  If there is a third  name,  it
       overrides the default name of the output file, which is ordinarily the same as the name of
       the input file (but on the current directory) with the extension .tex.  If you  just  want
       to  change the output file name, but don’t have a change file to apply, you can use `-' as
       the second argument.


       CWEBbin tries hard to be a drop-in replacement for CWEB, so  in  general  you  should  not
       notice  any  differences in invoking the programs nor in the resulting output.  There are,
       however, a few differences worth noting:

       • Options --help, --quiet, --verbose, --version, and flags -i, -o,  and  +lX  are  new  in
         CWEBbin and TeX Live.

       • Option  +lX  is  accompanied  by  several  wrapper files for cwebmac.tex with translated
         captions for German (+ld), French (+lf), and Italian (+li).

       • CWEB in TeX Live operates silently by default (as of 2019); use the --verbose option  to
         get the original behavior.

       • File  lookup  with  the  environment  variable CWEBINPUTS is extended to permit several,
         colon-separated, paths.

       • If properly configured, the main programs ctangle and cweave are localized with the “GNU
         gettext utilities”.


       Options  on the command line may be either turned off with `-' (if they are on by default)
       or turned on with `+' (if they are off by default).  In fact, the  options  are  processed
       from  left  to  right, so a sequence like --verbose -h will only show the banner line (+b)
       and the progress report (+p), but leave out the happy message (-h).

       The first batch of options are common to both ctangle and cweave:

       • +b: print banner line on terminal

       • +h: print success message on completion

       • +p: print progress report messages

       • +q/-q: shortcut for -bhp; also --quiet (default)

       • +v/-v: shortcut for +bhp; also --verbose+s: print usage statistics

       • --help: display help message and exit

       • --version: output version information and exit

       There are six other options applicable to cweave only:

       • -e: do not enclose C/C++ material in \PB{...}-f: do not force a newline after every C/C++ statement in output

       • -i: suppress indentation of parameter declarations

       • -o: suppress separation of declarations and statements

       • -x: omit indices, section names, table of contents

       • +lX/-lX: use macros for language X as of Xcwebmac.tex


       The environment variable CWEBINPUTS is used to search for the input files, or  the  system
       default if CWEBINPUTS is not set.  See tex(1) for the details of the searching.

       If   prepared   for   NLS  support,  ctangle  and  cweave  use  the  environment  variable
       TEXMFLOCALEDIR to configure the parent directory where the “GNU gettext utilities”  search
       for translation catalogs.

       These variables are preconfigured in TeX Live’s texmf.cnf.


       The location of the files mentioned below varies from system to system.  Use the kpsewhich
       utility to find their locations.

       • cwebmac.tex: The default TeX macros \input in the first line of the cweave output file.

       • cwebman.tex:    The    CWEB    user    manual,    available    in    PDF    from    CTAN


       • The  CWEB  System  of  Structured  Documentation:  by  Donald  E. Knuth  and Silvio Levy
         (hardcopy version of cwebman.tex and the source code listings  of  common.w,  ctangle.w,
         and cweave.w).

       • Literate Programming: by D. E. Knuth.

       • Weaving a Program: by Wayne Sewell.

       cweb(1), tex(1), cc(1)


       Don Knuth wrote WEB for TeX and Pascal.
       Silvio  Levy  designed  and  developed  CWEB  by  adapting the WEB conventions to C and by
       recoding everything in CWEB.  Knuth began using CWEB and made further  refinements.   Many
       other helpers are acknowledged in the CWEB manual.
       As  of  2019,  the CWEB system in TeX Live is based on the CWEBbin extension that collects
       ideas   and   improvements   from   numerous   contributors;   see   the   project    page