phpman > man > CWEB(1)

CWEB(1)                                General Commands Manual                               CWEB(1)



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 describ‐
       ing the program in as much detail as the writer may desire.  The user of CWEB ought to be fa‐
       miliar 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  out‐
       put 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, 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: ignore temporary output irrespective of 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

       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 de‐
       fault if CWEBINPUTS is not set.  See tex(1) for the details of the searching.  To avoid  con‐
       flicts 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 2022/dev                              June 6, 2021                                     CWEB(1)