WEB(1L)

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

SYNOPSIS
ctangle [ -bhpl ] [ +cs+ ] cwebfile[.w] [(changefile[.ch]|+|-) [outputfile[.c]]]
cweave [ -bhpx ] [ +cs+dtefauwm ] [ +isearchpath ] cwebfile[.w] [(changefile[.ch]|+|-) [outputfile[.tex]]]

DESCRIPTION
The ctangle program converts a CWEB source document into a C program that may be compiled in the usual way. The output file includes #line specifications so that error reporting and 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-reference 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 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 have some familiarity with TeX as well as knowledge of C.

The command line should have one, two, or three names on it. The first is taken as the CWEB file (and `.w' is added if there is no extension). If that file cannot be opened, the extension `.web' is tried instead. If there is a second name, it is a change file (and `.ch' is added if there is no extension), otherwise the name of the CWEB file with its extension replaced by `.ch' is tried as change file name; if there no such file, no change file is used. Instead of a change file one may specify `-' or `+'; `-' means do not use a change file, and `+' means use a change file only if a file of the default name exists (just as if only one name was given). The change file overrides parts of the CWEB file, as described in the documentation. A third name, if present, specifies the output file name explicitly. The default output file name is that of the CWEB file with extension `.c' (for ctangle ) or `.tex' (for cweave ); the default extension is also applied if a third name is given without extension.

Options in the command line may be either turned on with `+' and off with `-'; several characters may follow in the same argument, which indicate several options that are turned on respectively off simultaneously. In fact, the options are processed from left to right, so a sequence like `-b +b' is equivalent to `+b' (which is the default).

The +b option shows a banner line on your terminal. The +h option shows a happy message if the processing was successful. The +p option shows progress reports (starred module numbers) as the processing takes place. If you say `-bhp', you get no terminal output but error messages.

The +c option emulates Levy/Knuth CWEB. The +s option prints statistics about memory usage at the end of a run (assuming that the programs have been compiled with the -DSTAT switch). By setting the option ++ one can select the C++ language instead of C.

The option -l is applicable to ctangle only; when selected, the C output is made more readable for humans by omitting #line directives and preserving layout and comments.

There are several other options applicable to cweave only. The option -x means omit the index and table of contents. By setting the option +d one causes cweave to report problems encountered in parsing the program fragments. With +t the index and module names will be written to separate files. With +e the table of contents is forced to start on a new sheet when using a two-sided printer. The options +f , +a , +u , +w , and +m change the style in which programs are formatted: +f means force a newline after every simple statement in the formatted output, and +a means also force a newline before every simple statement, even if it follows a label or a condition; the option +u will change the style so that a line break goes after `{' instead of before, thus preventing them from aligning with their matching `}' (this is the style of Levy/Knuth CWEB), while the option +w puts a line break both before and after `{', producing a more symmetric layout at the expense of some extra paper. Finally, the option +m avoids forcing line breaks between successive declarations in a local block. With the option +isearchpath one can specify a place to look for header files, when they are not found in the current directory. The string following the `+i' will be stored and prepended to a header file name if it cannot be found otherwise (so the string should probably end with a pathname separator '/'). More than one such search path can be specified; they will be tried in order from left to right.

FILES
/usr/local/lib/tex/macros/cwebxmac.tex TeX macros used by cweave output.
/usr/local/lib/tex/macros/cwebcmac.tex TeX macros used in compatibility mode.
/usr/local/doc/cweb/manual.tex The user manual.

SEE ALSO
Literate Programming by D. E. Knuth. (CSLI, Stanford, 1992)
tex(1), cc(1), web(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. Frank Jensen adapted the programs to ANSI/ISO C, and Marc van Leeuwen made numerous changes for version x3.0, and wrote a new manual.

BUGS
The syntactic support for C++ does not cover that language completely, so formatting of complex C++ code may be bad.