Editing International Obfuscated C Code Contest

{{short description|Computer programming contest}}
{{primary sources|date=November 2011}}
{{Infobox recurring event
|name              = <!--Uses page name if omitted-->
|native_name       = 
|native_name_lang  = 
|logo              = File:IOCCC.png
|logo_alt          =
|logo_caption      = The logo of the IOCCC
|logo_size         =
|image             = 
|image_size        =
|alt               =
|caption           = 
|status            = Active
|genre             = Coding contest              
|frequency         = Semi-annually
|venue             = 
|location          = 
|coordinates       = <!-- {{coord|LAT|LON|type:event|display=inline,title}} --> 
|country           = 
|years_active      = 1984–1996, 1998, 2000, 2001, 2004–2006, 2011–2015, 2018-2020
|first             = {{start date|1984}}
|founders          = [[Landon Curt Noll]], Larry Bassel
|last              = 2020 <!-- Date of most recent event; if the event will not be held again, use {{End date|YYYY|MM|DD|df=y}} -->
|prev              = 
|next              = 
|participants      = 
|activity          = 
|leader_name       =
|patron            = 
|organised         = <!-- "organized=" also works -->
|filing            = 
|people            = 
|member            = 
|sponsor           = <!-- | or sponsors = -->
|website           = {{URL|https://www.ioccc.org|www.ioccc.org}}
|current           = 
|footnotes         = 
}}
The '''International Obfuscated C Code Contest''' (abbreviated '''IOCCC''') is a [[computer programming]] contest for [[Source code|code]] written in [[C (programming language)|C]] that is the most creatively [[obfuscated code|obfuscated]]. Held semi-annually, it is described as "celebrating [C's] syntactical opaqueness".<ref>{{cite journal |url=http://pcworld.co.nz/pcworld/pcw.nsf/how-to/beyond-the-command-line |access-date=2013-04-07 |title=Beyond the command line |journal=PC World New Zealand|last=Palmer|first=Geoff|date=November 1, 2004 |url-status=dead |archive-url=https://web.archive.org/web/20130210081342/http://pcworld.co.nz/pcworld/pcw.nsf/how-to/beyond-the-command-line |archive-date=February 10, 2013 }}</ref> The winning code for the 27th contest, held in 2020, was released in July 2020.<ref>{{cite web |url=https://www.ioccc.org/years-spoiler.html |title=Previous IOCCC Winners with spoilers |access-date=2023-05-01 |publisher=IOCCC}}</ref> Previous contests were held in the years 1984–1996, 1998, 2000, 2001, 2004–2006, 2011–2015 and 2018–2020.

Entries are evaluated anonymously by a panel of judges. The judging process is documented in the competition guidelines<ref name=guidelines>{{cite web |url=https://www.ioccc.org/2015/guidelines.txt |title=2015 Guidelines |access-date=2023-05-01 |year=2015 |format=plain text |publisher=IOCCC}}</ref> and consists of elimination rounds. By tradition, no information is given about the total number of entries for each competition. Winning entries are awarded with a category, such as "Worst Abuse of the [[C preprocessor]]" or "Most Erratic Behavior", and then announced on the official IOCCC website. The contest states that being announced on the IOCCC website is the reward for winning.

==History==

The IOCCC was started by [[Landon Curt Noll]] and Larry Bassel in 1984 while employed at National Semiconductor's Genix porting group. The idea for the contest came after they compared notes with each other about some poorly written code that they had to fix, notably the [[Bourne shell]], which used macros to emulate [[ALGOL 68]] syntax, and a buggy version of [[finger (Unix)|finger]] for BSD.<ref>{{cite web |url=https://www.ioccc.org/faq.html |title=The FAQ |publisher=IOCCC |access-date=2023-05-01}}</ref> The contest itself was the topic of a quiz question in the 1993 Computer Bowl.<ref>[http://nl.newsbank.com/nl-search/we/Archives?p_product=SJ&s_site=mercurynews&p_multi=SJ&p_theme=realcities&p_action=search&p_maxdocs=200&p_topdoc=1&p_text_direct-0=0EB71B1E74EA9019&p_field_direct-0=document_id&p_perpage=10&p_sort=YMD_date:D&s_trackval=GooglePM "Top Execs Fail To Compute Correctly"]. ''[[San Jose Mercury News]]'', California. May 15, 1993. p. 1A. Via [[Newsbank]]. {{subscription required}}</ref> After a hiatus of five years starting in 2006, the contest returned in 2011.<ref name=SJMerc11>{{cite web|url=https://www.pcworld.com/article/478306/obfuscated_code_contest_returns.html |title=Obfuscated Code Contest Returns |magazine=[[PC World]]|date=November 15, 2011|last=Jackson|first=Joab|access-date=2023-05-01}}</ref>

Compared with other programming contests, the IOCCC is described as "not all that serious" by [[Michael Swaine (technical author)|Michael Swaine]], editor of ''[[Dr. Dobb's Journal]]''.<ref>{{cite journal |url=https://www.drdobbs.com/architecture-and-design/there-must-be-contest/207404123 |title=There Must be Contest |first=Michael |last=Swaine |author-link=Michael Swaine (technical author) |journal=[[Dr. Dobb's Journal]]|date=May 1, 2008 |access-date=2023-05-01}}</ref>

==Rules==

Each year, the rules of the contest are published on the IOCCC website. All material is published under [[Creative Commons license]] [[Share-alike|BY-SA]] 3.0 Unported.<ref>[https://www.ioccc.org/ IOCCC home page, footer], and in each hint.txt file</ref> Rules vary from year to year and are posted with a set of guidelines that attempt to convey the spirit of the rules.

{{Blockquote|text=Hacking the contest rules is a tradition. — Landon Curt Noll, 2011<ref name=SJMerc11 />}}

The rules are often deliberately written with loopholes that contestants are encouraged to find and abuse.<ref name=guidelines /> Entries that take advantage of loopholes can cause the rules for the following year's contest to be adjusted.<ref name=guidelines />

==Obfuscations employed==

Entries often employ strange or unusual tricks, such as using the [[C preprocessor]] to do things it was not designed to do (in some cases "spectacularly", according to ''Dr. Dobbs'',<ref>{{cite web |url=https://www.drdobbs.com/open-source/code-finessing/193104882?pgno=2 |title=Code Finessing |magazine=[[Dr. Dobb's Journal]]|author=Spinellis, Diomidis |date=October 5, 2006 |access-date=2023-05-01}}</ref> with one entry creating an 11-bit [[Arithmetic logic unit|ALU]] in the C preprocessor<ref name="cpp_abuse">[https://www.ioccc.org/2004/vik2.hint IOCCC 2004 – Best Abuse of CPP]'' IOCCC. Retrieved 2023-05-01.</ref>), or avoiding commonly used constructs in the C programming language in favor of much more obscure ways of achieving the same thing.

Contributions have included source code formatted to resemble images, text, etc., after the manner of [[ASCII art]], preprocessor redefinitions to make code harder to read, and [[self-modifying code]]. In several years an entry was submitted that required a new definition of some of the rules for the next year, regarded as a high honor. An example is the world's shortest [[Quine (computing)|self-reproducing program]]. The entry was a program designed to output its own source code, and which had zero bytes of source code. When the program ran, it printed out zero bytes, equivalent to its source code.<ref>{{cite web|year=1994|title=smr.hint|url=https://www.ioccc.org/1994/smr.hint|access-date=2006-09-16|publisher=IOCCC|format=plain text}}</ref>

In the effort to take obfuscation to its extremes, contestants have produced programs which skirt around the edges of C standards, or result in constructs which trigger rarely used code path combinations in compilers. As a result, several of the past entries may not compile directly in a modern compiler, and some may cause crashes.

==Examples==
Within the code size limit of only a few kilobytes, contestants have managed to do complicated things – a 2004 winner turned out an operating system.<ref>{{cite web| url=https://www.ioccc.org/2004/gavin.hint |title=gavin.hint3 |year=2004 |format=plain text |publisher=IOCCC |access-date=2023-05-01}}</ref>

===Toledo Nanochess===
''Toledo Nanochess'' is a [[chess engine]] created by Mexican software developer Oscar Toledo Gutiérrez, a five-time winner of the IOCCC. In accordance with IOCCC rules, it is 1255 characters long. The author claims that it is the world's smallest chess program written in C.

The source code for ''Toledo Nanochess'' and other engines is available.<ref>{{cite web |url=https://nanochess.org/chess3.html |title=Toledo Nanochess and Toledo Picochess}}</ref>
Because ''Toledo Nanochess'' is based on Toledo's winning entry from the 18th IOCCC (Best Game<ref>{{cite web |url=https://www.ioccc.org/winners.html#Oscar_Toledo_G. |title=Winners: The authors of winning IOCCC entries}}</ref>), it is heavily [[obfuscated code|obfuscated]].<ref>{{cite web |url=https://github.com/bormand/nanochess |title=Nanochess partially de-obfuscated version |website=[[GitHub]] |access-date=1 May 2023}}</ref>

On February 2, 2014, the author published the book ''Toledo Nanochess: The commented source code'', which contains the fully commented source code.<ref>{{Cite book|title=Toledo Nanochess: The commented source code|isbn=978-1-304-86437-6|first=Oscar|last=Toledo Gutiérrez|year=2014|publisher=[[Lulu (company)|Lulu]]}}</ref>

As of February 7, 2010, it appears to be one of only two chess engines written in less than 2 kilobytes of C that are able to play full legal chess moves, along with ''Micro-Max'' by Dutch physicist H. G. Muller. In 2014 the 1 kilobyte barrier was broken by ''Super Micro Chess''<ref>{{Cite web|url=https://smmax.sourceforge.net|title=Super Micro Chess Engine - Home Page - Extremely Compact C Source and Executable Program Size|website=smmax.sourceforge.net}}</ref> – a derivative of Micro-Max – totaling 760 characters (spaces and newlines included).<ref>{{cite web |url=https://sourceforge.net/projects/smmax/files/sm-fide%20760.c/download |title=Super Micro FIDE 760}}</ref> There is also a smaller version of Toledo's engine, the ''Toledo Picochess'', consisting of 944 non-blank characters.

'''Source code excerpt'''
<syntaxhighlight lang="c">
B,i,y,u,b,I[411],*G=I,x=10,z=15,M=1e4;X(w,c,h,e,S,s){int t,o,L,E,d,O=e,N=-M*M,K
=78-h<<x,p,*g,n,*m,A,q,r,C,J,a=y?-x:x;y^=8;G++;d=w||s&&s>=h&&v 0,0)>M;do{_ o=I[
p=O]){q=o&z^y _ q<7){A=q--&2?8:4;C=o-9&z?q["& .$  "]:42;do{r=I[p+=C[l]-64]_!w|p
==w){g=q|p+a-S?0:I+S _!r&(q|A<3||g)||(r+1&z^y)>9&&q|A>2){_ m=!(r-2&7))P G[1]=O,
K;J=n=o&z;E=I[p-a]&z;t=q|E-7?n:(n+=2,6^y);Z n<=t){L=r?l[r&7]*9-189-h-q:0 _ s)L
+=(1-q?l[p/x+5]-l[O/x+5]+l[p%x+6]*-~!q-l[O%x+6]+o/16*8:!!m*9)+(q?0:!(I[p-1]^n)+
!(I[p+1]^n)+l[n&7]*9-386+!!g*99+(A<2))+!(E^y^9)_ s>h||1<s&s==h&&L>z|d){p[I]=n,O
[I]=m?*g=*m,*m=0:g?*g=0:0;L-=X(s>h|d?0:p,L-N,h+1,G[1],J=q|A>1?0:p,s)_!(h||s-1|B
-O|i-n|p-b|L<-M))P y^=8,u=J;J=q-1|A<7||m||!s|d|r|o<z||v 0,0)>M;O[I]=o;p[I]=r;m?
*m=*g,*g=0:g?*g=9^y:0;}_ L>N){*G=O _ s>1){_ h&&c-L<0)P L _!h)i=n,B=O,b=p;}N=L;}
n+=J||(g=I+p,m=p<O?g-3:g+2,*m<z|m[O-p]||I[p+=p-O]);}}}}Z!r&q>2||(p=O,q|A>2|o>z&
!r&&++C*--A));}}}Z++O>98?O=20:e-O);P N+M*M&&N>-K+1924|d?N:0;}main(){Z++B<121)*G
++=B/x%x<2|B%x<2?7:B/x&4?0:*l++&31;Z B=19){Z B++<99)putchar(B%x?l[B[I]|16]:x)_
x-(B=F)){i=I[B+=(x-F)*x]&z;b=F;b+=(x-F)*x;Z x-(*G=F))i=*G^8^y;}else v u,5);v u,
1);}}</syntaxhighlight>

===Pi===
Below is a 1988 entry which calculates [[pi]] by looking at its own [[area]]:<ref>[https://www.ioccc.org/1988/westley.c "westley.c"], 5th International Obfuscated C Code Contest 1988</ref>

<syntaxhighlight lang="c">
#define _ -F<00||--F-OO--;
int F=00,OO=00;main(){F_OO();printf("%1.3f\n",4.*-F/OO/OO);}F_OO()
{
            _-_-_-_
       _-_-_-_-_-_-_-_-_
    _-_-_-_-_-_-_-_-_-_-_-_
  _-_-_-_-_-_-_-_-_-_-_-_-_-_
 _-_-_-_-_-_-_-_-_-_-_-_-_-_-_
 _-_-_-_-_-_-_-_-_-_-_-_-_-_-_
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
 _-_-_-_-_-_-_-_-_-_-_-_-_-_-_
 _-_-_-_-_-_-_-_-_-_-_-_-_-_-_
  _-_-_-_-_-_-_-_-_-_-_-_-_-_
    _-_-_-_-_-_-_-_-_-_-_-_
        _-_-_-_-_-_-_-_
            _-_-_-_
}
</syntaxhighlight>

(This entry was written in [[K&R C]]; it does not work correctly in ANSI C without some changes.<ref>using gcc, compile with the following command line: <syntaxhighlight lang="console">$ gcc -traditional-cpp -o r r.c</syntaxhighlight> or <syntaxhighlight lang="console">$ gcc -E r.c | sed 's/- -/--/g' > r2.c ; gcc -o r2 r2.c</syntaxhighlight> (The source file is <code>r.c</code>){{Original research inline|date=April 2017}}</ref>)

===Flight simulator===
Another example is the following flight simulator, the winner of the 1998 IOCCC,<ref name=":0">[https://blog.aerojockey.com/post/iocccsim Carl Banks' Blog: IOCCC Flight Simulator]. blog.aerojockey.com. Retrieved 2023-05-01.</ref> as listed and described in ''Calculated Bets: Computers, Gambling, and Mathematical Modeling to Win'' (2001)<ref>{{cite book |title= Calculated Bets: Computers, Gambling, and Mathematical Modeling to Win |url= https://archive.org/details/calculatedbetsco0000skie |url-access= registration |author=Skiena, Steven |pages=[https://archive.org/details/calculatedbetsco0000skie/page/152 152], 153 |publisher=The Mathematical Association of America|year=2001|isbn=978-0521009621}}</ref> and shown below:

<syntaxhighlight lang="c">
#include                                     <math.h>
#include                                   <sys/time.h>
#include                                   <X11/Xlib.h>
#include                                  <X11/keysym.h>
                                          double L ,o ,P
                                         ,_=dt,T,Z,D=1,d,
                                         s[999],E,h= 8,I,
                                         J,K,w[999],M,m,O
                                        ,n[999],j=33e-3,i=
                                        1E3,r,t, u,v ,W,S=
                                        74.5,l=221,X=7.26,
                                        a,B,A=32.2,c, F,H;
                                        int N,q, C, y,p,U;
                                       Window z; char f[52]
                                    ; GC k; main(){ Display*e=
 XOpenDisplay( 0); z=RootWindow(e,0); for (XSetForeground(e,k=XCreateGC (e,z,0,0),BlackPixel(e,0))
; scanf("%lf%lf%lf",y +n,w+y, y+s)+1; y ++); XSelectInput(e,z= XCreateSimpleWindow(e,z,0,0,400,400,
0,0,WhitePixel(e,0) ),KeyPressMask); for(XMapWindow(e,z); ; T=sin(O)){ struct timeval G={ 0,dt*1e6}
; K= cos(j); N=1e4; M+= H*_; Z=D*K; F+=_*P; r=E*K; W=cos( O); m=K*W; H=K*T; O+=D*_*F/ K+d/K*E*_; B=
sin(j); a=B*T*D-E*W; XClearWindow(e,z); t=T*E+ D*B*W; j+=d*_*D-_*F*E; P=W*E*B-T*D; for (o+=(I=D*W+E
*T*B,E*d/K *B+v+B/K*F*D)*_; p<y; ){ T=p[s]+i; E=c-p[w]; D=n[p]-L; K=D*m-B*T-H*E; if(p [n]+w[ p]+p[s
]== 0|K <fabs(W=T*r-I*E +D*P) |fabs(D=t *D+Z *T-a *E)> K)N=1e4; else{ q=W/K *4E2+2e2; C= 2E2+4e2/ K
 *D; N-1E4&& XDrawLine(e ,z,k,N ,U,q,C); N=q; U=C; } ++p; } L+=_* (X*t +P*M+m*l); T=X*X+ l*l+M *M;
  XDrawString(e,z,k ,20,380,f,17); D=v/l*15; i+=(B *l-M*r -X*Z)*_; for(; XPending(e); u *=CS!=N){
                                   XEvent z; XNextEvent(e ,&z);
                                       ++*((N=XLookupKeysym
                                         (&z.xkey,0))-IT?
                                         N-LT? UP-N?& E:&
                                         J:& u: &h); --*(
                                         DN -N? N-DT ?N==
                                         RT?&u: & W:&h:&J
                                          ); } m=15*F/l;
                                          c+=(I=M/ l,l*H
                                          +I*M+a*X)*_; H
                                          =A*r+v*X-F*l+(
                                          E=.1+X*4.9/l,t
                                          =T*m/32-I*T/24
                                           )/S; K=F*M+(
                                           h* 1e4/l-(T+
                                           E*5*T*E)/3e2
                                           )/S-X*d-B*A;
                                           a=2.63 /l*d;
                                           X+=( d*l-T/S
                                            *(.19*E +a
                                            *.64+J/1e3
                                            )-M* v +A*
                                            Z)*_; l +=
                                            K *_; W=d;
                                            sprintf(f,
                                            "%5d  %3d"
                                            "%7d",p =l
                                           /1.7,(C=9E3+
                              O*57.3)%0550,(int)i); d+=T*(.45-14/l*
                             X-a*130-J* .14)*_/125e2+F*_*v; P=(T*(47
                             *I-m* 52+E*94 *D-t*.38+u*.21*E) /1e2+W*
                             179*v)/2312; select(p=0,0,0,0,&G); v-=(
                              W*F-T*(.63*m-I*.086+m*E*19-D*25-.11*u
                               )/107e2)*_; D=cos(o); E=sin(o); } }
</syntaxhighlight>
[[File:1998_IOCCC_Flight_simulator_screenshot.png|thumb|Pittsburgh scenery of the Flight simulator]]
This program needs the following command line on a Linux system to be compiled:<ref name=":0" />
<syntaxhighlight lang="console">
$ cc banks.c -o banks -DIT=XK_Page_Up -DDT=XK_Page_Down \
	-DUP=XK_Up -DDN=XK_Down -DLT=XK_Left -DRT=XK_Right \
	-DCS=XK_Return -Ddt=0.02 -lm -lX11 -L/usr/X11R6/lib
</syntaxhighlight>

In order to run the binary file ({{code|banks}}) it has to be supplied with a {{code|.sc}} scenery file via [[standard input|{{code|stdin}}]] input:<ref name=":0" />
<syntaxhighlight lang="console">$ cat pittsburgh.sc | ./banks </syntaxhighlight>

===Akari===
Below is a 2011 entry which downsamples [[Netpbm#PGM_example|PGM]], [[Netpbm#PPM_example|PPM]] images and ASCII art (of Akari from ''[[YuruYuri]]'') by Don, Yang:<ref>{{Cite web|title=Winners: The authors of winning IOCCC entries |url=https://www.ioccc.org/years.html#2011_akari |access-date=2023-05-01 |website=www.ioccc.org}}</ref>

<syntaxhighlight lang="c">
                                       /*
                                      +
                                     +
                                    +
                                    +
                                    [         >i>n[t
                                     */   #include<stdio.h>
                        /*2w0,1m2,]_<n+a m+o>r>i>=>(['0n1'0)1;
                     */int/**/main(int/**/n,char**m){FILE*p,*q;int        A,k,a,r,i/*
                   #uinndcelfu_dset<rsitcdti_oa.nhs>i/_*/;char*d="P%"   "d\n%d\40%d"/**/
                 "\n%d\n\00wb+",b[1024],y[]="yuriyurarararayuruyuri*daijiken**akkari~n**"
          "/y*u*k/riin<ty(uyr)g,aur,arr[a1r2a82*y2*/u*r{uyu}riOcyurhiyua**rrar+*arayra*="
       "yuruyurwiyuriyurara'rariayuruyuriyuriyu>rarararayuruy9uriyu3riyurar_aBrMaPrOaWy^?"
      "*]/f]`;hvroai<dp/f*i*s/<ii(f)a{tpguat<cahfaurh(+uf)a;f}vivn+tf/g*`*w/jmaa+i`ni("/**
     */"i+k[>+b+i>++b++>l[rb";int/**/u;for(i=0;i<101;i++)y[i*2]^="~hktrvg~dmG*eoa+%squ#l2"
     ":(wn\"1l))v?wM353{/Y;lgcGp`vedllwudvOK`cct~[|ju {stkjalor(stwvne\"gt\"yogYURUYURI"[
     i]^y[i*2+1]^4;/*!*/p=(n>1&&(m[1][0]-'-'||m[1][1]  !='\0'))?fopen(m[1],y+298):stdin;
      /*y/riynrt~(^w^)],]c+h+a+r+*+*[n>)+{>f+o<r<(-m]    =<2<5<64;}-]-(m+;yry[rm*])/[*
       */q=(n<3||!(m[2][0]-'-'||m[2][1]))?stdout /*]{     }[*/:fopen(m[2],d+14);if(!p||/*
       "]<<*-]>y++>u>>+r >+u+++y>--u---r>++i+++"  <)<      ;[>-m-.>a-.-i.++n.>[(w)*/!q/**/)
    return+printf("Can "  "not\x20open\40%s\40"    ""       "for\40%sing\n",m[!p?1:2],!p?/*
  o=82]5<<+(+3+1+&.(+  m  +-+1.)<)<|<|.6>4>-+(>    m-        &-1.9-2-)-|-|.28>-w-?-m.:>([28+
 */"read":"writ");for  (   a=k=u= 0;y[u];  u=2    +u){y[k++   ]=y[u];}if((a=fread(b,1,1024/*
,mY/R*Y"R*/,p/*U*/)/*          R*/ )>/*U{  */   2&& b/*Y*/[0]/*U*/=='P' &&4==/*"y*r/y)r\}
*/sscanf(b,d,&k,& A,&           i,  &r)&&        !   (k-6&&k -5)&&r==255){u=A;if(n>3){/*
]&<1<6<?<m.-+1>3> +:+ .1>3+++     .   -m-)      -;.u+=++.1<0< <; f<o<r<(.;<([m(=)/8*/
u++;i++;}fprintf   (q,    d,k,           u      >>1,i>>1,r);u  = k-5?8:4;k=3;}else
  /*]>*/{(u)=/*{   p> >u  >t>-]s                >++(.yryr*/+(    n+14>17)?8/4:8*5/
     4;}for(r=i=0  ;  ;){u*=6;u+=                (n>3?1:0);if    (y[u]&01)fputc(/*
      <g-e<t.c>h.a r  -(-).)8+<1.                 >;+i.(<)<     <)+{+i.f>([180*/1*
      (r),q);if(y[u   ]&16)k=A;if                               (y[u]&2)k--;if(i/*
      ("^w^NAMORI; {   I*/==a/*"                               )*/){/**/i=a=(u)*11
       &255;if(1&&0>=     (a=                                 fread(b,1,1024,p))&&
        ")]i>(w)-;} {                                         /i-f-(-m--M1-0.)<{"
         [ 8]==59/* */                                       )break;i=0;}r=b[i++]
            ;u+=(/**>>                                     *..</<<<)<[[;]**/+8&*
            (y+u))?(10-              r?4:2):(y[u]         &4)?(k?2:4):2;u=y[u/*
             49;7i\(w)/;}             y}ru\=*ri[        ,mc]o;n}trientuu ren (
             */]-(int)'`';}             fclose(          p);k= +fclose( q);
              /*] <*.na/m*o{ri{                       d;^w^;}  }^_^}}
               "   */   return  k-                -1+   /*\'   '-`*/
                     (   -/*}/   */0x01        );       {;{    }}
                            ;           /*^w^*/        ;}
</syntaxhighlight>

If the program is run using its own source as the input, the result is:
<syntaxhighlight lang="c">
$ ./akari akari.c 
                   
                  
                       int
            *w,m,_namori=('n');
         #include<stdio.h>/*;hrd"%  dnd4%"*/
     /**/int(y),u,r[128*2/*{y}icuhya*rr*rya=
   */];void/**/i(){putchar(u);}int/**/main(/*
  "(n"l)?M5{YlcpvdluvKct[j skao(tve"t"oYRYR"
   */int(w),char**n){for(m  =256;--m;r[m]/*
   "<*]y+u>r>u+y-u-r+i+" )   ;>m.a.i+n>()/q*/
 =25<(31&( m -1))||64-(  m    &192)||2>w?m:(2+
m/*"*,/U//     R/)/U *  & /Y/0/U/=P &=/"*/)\
&16?m-13 : 13+     m)   ;u=+10 ;for(;(m=/*
 *>/()/{ p u t-s        +(yy*+  n1>7?/:*/
   getchar ())+1         ;i()   ){if(10/*
   "wNMR;{ I/=/"               )/{*/==u*1
    )i();                      if(m-10){
      u=/*>                  *./<)[;*/8*
      4;i();       }u=r[    m];}return(
       * *n/*{i            ;w; }_}
          ( -*/ *00    )    ;  }
$ ./akari akari.c > ./akari.small
$ ./akari ./akari.small 
         
      wm_aoi(n)
  /*ity,,[2*/{}char*y=
 (")M{lpduKtjsa(v""YY"
 "*yuruyuri") ;main(/*
/",U/  R)U*  Y0U= ="/\
*/){puts    (y+ 17/*
 "NR{I="       ){/=*
   =*         */);/*
   **/{      ;;}}
$ 
$ ./akari ./akari.small > ./akari.smaller
$ ./akari ./akari.smaller
   main
(){puts("Y"
"U RU YU "\
"RI"   )/*
 */   ;}
$
</syntaxhighlight>

==See also==
*[[Obfuscated Perl Contest]]
*[[Underhanded C Contest]]
*[[Esoteric programming language]]

==Notes and references==
<references />

==External links==
*{{official|https://www.ioccc.org/}}

[[Category:C (programming language) contests]]
[[Category:Computer humour]]
[[Category:Software obfuscation]]
[[Category:Ironic and humorous awards]]
[[Category:Recurring events established in 1984]]