NAME

       ctangle, cweave - translate CWEB to C/C++ and/or TeX

SYNOPSIS

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

DESCRIPTION

       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++.

USAGE

       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.

DIFFERENCES TO ORIGINAL CWEB

       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 +c, -i, -o, +u, 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; see ENVIRONMENT below.

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

OPTIONS

       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

       • +c: check temporary output for changes

       • +s: print usage statistics

       • --help: display help message and exit

       • --version: output version information and exit

       There are two other options applicable to ctangle only:

       • +k: keep separators in numeric literals in the output

       • +u: transliterate UTF-8 characters in C code

       There are eight 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

       • -F: do not force a compound statement to start on a new line

       • -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

       • +t: treat typename in a template like typedef

ENVIRONMENT

       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.  To avoid conflicts with other
       programs that also use the CWEBINPUTS environment, you can be more specific and use  CWEBINPUTS_cweb  for
       special requirements in CWEB.

       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.

FILES

       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.

SEE ALSO

       • 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)

AUTHORS

       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.
       Contemporary development on https://github.com/ascherer/cweb.

Web2c 2025/dev                                   March 10, 2024                                          CWEB(1)