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rsTeX and related programs


This is a manual translation of tex.web version 3.14159265 into standard C++. Mostly it's a direct translation of the original pascal source with very minimal changes. The amount of C++ (that is not also C) used is very minimal. Notably I added an array class to keep the same indexing as in the original and to also get boundschecking.

What is the purpose of this program? Well, I've long been fascinated by Donald Knuth and his work and especially TeX. TeX is one of the most well documented programs out there and the source code is of course readily available but, one lacking feature of current implementations is that because the source code is machine converted into C it's not easy to understand or step through the code in a debugger. So that's why I decided to translate the program to C++. By doing so one also hopefully gains some understanding of what the code does.

Another aspect was that I was interested in knowing how long it would take to write the program. I didn't keep a stop watch at hand but a rough estimate is that it took about 30 hours to type the whole program in and more than twice that to fix all typos and other bugs introduced before it finally passed the trip test. Which was kind of what I expected except I thought the debugging time would be on par with the time it took to type it in. Had I been more systematic in my approach and introduced more asserts and checks from the beginning the debugging time would have been considerably shorter.

The program consists of two files rstex.h.pre and rstex.cpp.pre. These two files must be preprocessed by another program which converts all special strings in the program to numbers (as the original tangle program does), and makes a string pool file. After this preprocessing we are left with three files rstex.h, rstex.cpp, and tex.pool. rstex.cpp can then be compiled by any non-ancient C++ compiler, and the executable can be run.

Notable omissions

  • Currently no path searching is done so all files the program needs are supposed to exist in the current directory. (See the Unix and Windows specific versions to avoid this).
  • No other files needed for a complete system is included, i.e. fmt files, fonts, tfm files macro packages etc.


This is NOT the official version of TeX, it is only based upon the official version of TeX. It may contain bugs not present in the official version. It does pass the trip test, but the trip test does not test everything. In no way shall the author of this program be responsible for any damages, direct or indirect, that may result out of its use. It is not meant to be a working typesetting system, it is meant for educational purpose, for those who want to understand how this complex software works.


I have also translated mf.web for Windows and Unix but currently only the Windows version supports graphical screen output.


A small program to view the original TeX font bitmaps (PXL, GF, PK, or MF). This program works on both Linux and Windows, and Mac but requires Qt to be installed.


Far from complete program to read DVI files, only for Windows at the moment but perhaps a Qt version will exist some day.


These programs are copyright (C) 2018 by Richard Sandberg (mylodon at gmail dot com). The original tex.web is copyright (C) 1982 by Donald Knuth.


These programs are for educational purpose only, all commercial use is strictly forbidden.




Manual translation of tex.web version 3.14159265 into C++ (and other related programs)








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