Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.lang.c Subject: Re: Sort of trivial code challenge - may be interesting to you anyway Date: Tue, 03 Mar 2026 06:20:33 -0800 Organization: A noiseless patient Spider Lines: 81 Message-ID: <86a4wpdmfi.fsf@linuxsc.com> References: <10n80sc$3soe4$1@dont-email.me> <86v7feei2e.fsf@linuxsc.com> <10o53k6$1i0ef$2@dont-email.me> <86ms0peby6.fsf@linuxsc.com> <10o6nci$21m76$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Date: Tue, 03 Mar 2026 14:20:39 +0000 (UTC) Injection-Info: dont-email.me; posting-host="9dc790098ce30bad4f358538e3d50880"; logging-data="2191717"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/ehk9AEVUS8v3ebZD5gq0Ja33fxLeK4Go=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:xgbVaXZbJ1EK1kIOvHh9u2wVeWY= sha1:l5H0I150Isi+tdKGaoGxmwp1az8= Xref: csiph.com comp.lang.c:396736 DFS writes: > On 3/3/2026 12:09 AM, Tim Rentsch wrote: > >> DFS writes: >> >>> On 3/2/2026 3:44 AM, Tim Rentsch wrote: >>> >>>> DFS writes: >>>> >>>> >>>> A straightfoward exercise. Here is a counter challenge to make >>>> things more interesting: as above, but don't use nested loops >>>> (or goto's, etc). >>> >>> Done. I should have added, I appreciate your taking on the challenge. > Recursion means the function calls itself. What you're describing is called direct recursion. The word recursion by itself, without the adjective, includes the case of mutually recursive functions. > [...] > >> The latest challenge, which I just got through doing, is to >> disallow if, for, while, goto, return, and to forbid functions >> and function calls except for calls to C standard library >> functions. > > Yikes! > > Is main() OK? Yes, sorry, not mentioning main() was an oversight on my part. (Still not okay to call it.) > How about the use of variables? Sure. > What written languages are allowed? Standard ISO C. Okay not to be strictly conforming. :) > nested ternaries? How deep? Sure. As deep as you can stand, within reason. My own code sometimes used ?: at the end of another ?: but not in the middle (ie, ... ? ... ? ... : ... : ... never appeared). >> Also no math library. :) > > Using math.h allowed me to easily create a one-line formula. > But I could probably now do it in 3-4 lines without math.h. Yes it isn't hard. >> The program is a bit on the long side because of argument >> processing but the matrix print code is less than 20 lines, >> including 5 blank lines. > > I'll have to bow out for now, but would like to see your latest code. My rule is not to post my own code until others have made a good faith effort on the challenge. > I note that the no-loops challenge was a worthwhile pursuit I never > even considered. Yes, no loops is fun. Once you get used to it, using tail-recursive functions in place of loops often seems like a better choice. > I think a recursive function could be really short and sweet, so I'm > going to try that. By all means. The version I first wrote had two tail-recursive functions, one to find the appropriate number of rows and columns for a given cutoff, and one to show the matrix of values.