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You might all enjoy The International Obfuscated C Code Contest https://www.ioccc.org/ https://www.ioccc.org/ https://www.ioccc.org/years.html https://www.iocc

You might all enjoy The International Obfuscated C Code Contest https://www.ioccc.org/ https://www.ioccc.org/ https://www.ioccc.org/years.html https://www.ioccc.org/years.html

hoseja 2y ago
Is the linked example a quine or something else? It's a quine, right?
- mananaysiempre 2y ago
  TFA? No, it’s a C / Bourne shell polyglot where the shell part compiles and runs the C part. I’ve also used this technique when I needed to post self-contained examples (e.g. to mailing lists), but I don’t know if people actually appreciated it.
lifthrasiir 2y ago
IOCCC is almost irrelevant here, but one particular winning entry is relevant: 2000/tomx [1]. Nowadays IOCCC is hosted in GitHub Pages and it is hard to look at the verbatim source, so the following is the entire source code: #include <stdio.h> #define true true /*:all CC=cc PROG=tomx false : make -f $0 $1 exit 0 all: $(PROG) %:%.c $(CC) $< -o $@ clean: rm $(PROG) .PHONY: /* true clean */ int main() {return!printf("Hello, world\n");} (All indentations here are actually tabs.) [1] https://www.ioccc.org/2000/tomx.c https://www.ioccc.org/2000/tomx.c
- rramadass 2y ago
  This compiles as both "./tomx.c" and "make -f tomx.c" to produce the executable "tomx"; but am not fully clear how?
  - lifthrasiir 2y ago
    As a shell script, anything starting with `#`, `true<WS>` and `false<WS>` are meant to be ignored and variable declarations are compatible with Make. The next lines to be executed are therefore `make -f $0 $1` and `exit 0`, as you would expect. Shell scripts are parsed linewise so subsequent lines are ignored. As a Makefile, again `#` lines are ignored and variable declarations are compatible but lines starting with `true<WS>` and `false<WS>` have to be a valid construct, so they are made into rules. Make doesn't rely much on the rule's recipe (you can do way more weird things by setting `SHELL` to non-shells by the way!), so indented lines are essentially ignored unless the rule is triggered. Next lines are usual stuffs for Makefile. As `true` (and anything follows, see the next paragraph) would be the first and thus default rule target, it has to trigger `all` manually and ensure that `all` is always executed in this way by setting the final `.PHONY` rule. As a C source code, `#` lines are now preprocessor directives and used to hide the first `true` token from the compiler. As an identifier followed by a colon wouldn't be a valid C code at the top level, `true` should be followed by a comment which extends to the second-to-last line. (There is no technical reason for `*/` to be a requisite here I believe.) The final line is an usual indented C code, which is a part of `.PHONY` which recipe is ignored. Since Make will interpret `/*` as path patterns, they have to be also handled by `.PHONY`.
    - rramadass 2y ago
      Nice. I worked out most of it; the C source part was easy and the Makefile was mostly comprehensible(except for the "true"/"false" rules) but the shell script part was what stumped me; now i see the sneaky whitespace in "false :". A true IOCCC winner. One tip for folks trying to figure out this (and other multi-modal) code is to use your editor's syntax highlight feature based on filetype. So for example in vim renaming this file to ".sh" and ".mk" gives you shell script and makefile structures.

You might all enjoy The International Obfuscated C Code Contest https://www.ioccc.org/ https://www.ioccc.org/ https://www.ioccc.org/years.html https://www.ioccc.org/years.html

hoseja 2y ago

Is the linked example a quine or something else? It's a quine, right?

mananaysiempre 2y ago
TFA? No, it’s a C / Bourne shell polyglot where the shell part compiles and runs the C part. I’ve also used this technique when I needed to post self-contained examples (e.g. to mailing lists), but I don’t know if people actually appreciated it.

lifthrasiir 2y ago

IOCCC is almost irrelevant here, but one particular winning entry is relevant: 2000/tomx [1]. Nowadays IOCCC is hosted in GitHub Pages and it is hard to look at the verbatim source, so the following is the entire source code: #include <stdio.h> #define true true /*:all CC=cc PROG=tomx false : make -f $0 $1 exit 0 all: $(PROG) %:%.c $(CC) $< -o $@ clean: rm $(PROG) .PHONY: /* true clean */ int main() {return!printf("Hello, world\n");} (All indentations here are actually tabs.) [1] https://www.ioccc.org/2000/tomx.c https://www.ioccc.org/2000/tomx.c

rramadass 2y ago
This compiles as both "./tomx.c" and "make -f tomx.c" to produce the executable "tomx"; but am not fully clear how?
- lifthrasiir 2y ago
  As a shell script, anything starting with `#`, `true<WS>` and `false<WS>` are meant to be ignored and variable declarations are compatible with Make. The next lines to be executed are therefore `make -f $0 $1` and `exit 0`, as you would expect. Shell scripts are parsed linewise so subsequent lines are ignored. As a Makefile, again `#` lines are ignored and variable declarations are compatible but lines starting with `true<WS>` and `false<WS>` have to be a valid construct, so they are made into rules. Make doesn't rely much on the rule's recipe (you can do way more weird things by setting `SHELL` to non-shells by the way!), so indented lines are essentially ignored unless the rule is triggered. Next lines are usual stuffs for Makefile. As `true` (and anything follows, see the next paragraph) would be the first and thus default rule target, it has to trigger `all` manually and ensure that `all` is always executed in this way by setting the final `.PHONY` rule. As a C source code, `#` lines are now preprocessor directives and used to hide the first `true` token from the compiler. As an identifier followed by a colon wouldn't be a valid C code at the top level, `true` should be followed by a comment which extends to the second-to-last line. (There is no technical reason for `*/` to be a requisite here I believe.) The final line is an usual indented C code, which is a part of `.PHONY` which recipe is ignored. Since Make will interpret `/*` as path patterns, they have to be also handled by `.PHONY`.
  - rramadass 2y ago
    Nice. I worked out most of it; the C source part was easy and the Makefile was mostly comprehensible(except for the "true"/"false" rules) but the shell script part was what stumped me; now i see the sneaky whitespace in "false :". A true IOCCC winner. One tip for folks trying to figure out this (and other multi-modal) code is to use your editor's syntax highlight feature based on filetype. So for example in vim renaming this file to ".sh" and ".mk" gives you shell script and makefile structures.