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 usu‐
       al 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  pro‐
       duce  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 or‐
       dinarily 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  differ‐
       ences  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 origi‐
         nal 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 utili‐
         ties”.

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  se‐
       quence  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 is one other option applicable to ctangle only:

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

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

       There are seven 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

       • +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  CWE‐
       BINPUTS 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 (https://ctan.org/pkg/cweb).

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 2023                                       August 20, 2022                                         CWEB(1)