explain this c code...

[sudhanshu]

This one is a puzzle a fren has challenged me to solve.
I tried it myself but could not get the complete answer.
so here I am to seek ur help.


Can anyone tell me the o/p of this c code without compiling...

main(_){for(--_;putchar(_++["SEJBT!SPDLT\1"]-1););}

on compiling it prints "RDIAS ROCKS".

[r035198x]

This one is a puzzle a fren has challenged me to solve.
I tried it myself but could not get the complete answer.
so here I am to seek ur help.


Can anyone tell me the o/p of this c code without compiling...

main(_){for(--_;putchar(_++["SEJBT!SPDLT\1"]-1););}

on compiling it prints "RDIAS ROCKS".

I'm not a c compiler but that code won't compile.
Is the puzzle supposed to be how to make it compile?

[JosAH]

I'm not a c compiler but that code won't compile.
Is the puzzle supposed to be how to make it compile?

Except for just the 'main(_)' thingie it compiles and it obfuscates matters by naming
the argc parameter '_' and by using a[i] as i[a] which is perfectly legal in C.
It prints all the characters from that string minus1, so the last character stops
the for loop; that program Sir, I consider baby obfuscation 101 :-P

kind regards,

Jos (<--- the grand DeObfuscator strikes again ;-)

[r035198x]

Except for just the 'main(_)' thingie it compiles and it obfuscates matters by naming
the argc parameter '_' and by using a[i] as i[a] which is perfectly legal in C.
It prints all the characters from that string minus1, so the last character stops
the for loop; that program Sir, I consider baby obfuscation 101 :-P

kind regards,

Jos (<--- the grand DeObfuscator strikes again ;-)

Argh, I was using a c++ compile command on it.

[Darryl]

This one is a puzzle a fren has challenged me to solve.
I tried it myself but could not get the complete answer.
so here I am to seek ur help.


Can anyone tell me the o/p of this c code without compiling...

main(_){for(--_;putchar(_++["SEJBT!SPDLT\1"]-1););}

on compiling it prints "RDIAS ROCKS".

Solve what? You ask can anyone tell the output of the Code and then turn around and say the output is "RDIAS ROCKS"

here's a rewrite to make it more understandable

int main( int argc, const char* argv[] )
{
     char str[] = "SEJBT!SPDLT\1";
 
     for (--argc; str[argc]-1 != 0; argc++)
     {
           putchar(str[i]-1);
     }
}

of course the program only works as expected if no command line parameters is used, otherswise for every parameter you'd lose 1 char at the front and with enough parameters you'd easily go past the end bound of the string.

Also as the last poster stated, the original code probably won't compile on most compilers, it is dependant on the compiler automatically assigning the variable "_" to an int which most compliant compilers now a days won't do but will instead produce an error.

[JosAH]

Argh, I was using a c++ compile command on it.

The body of that ugly little thingy is still valid C++ ...

kind regards,

Jos (programming language lawyer par excellance ;-)

[Darryl]

The body of that ugly little thingy is still valid C++ ...

kind regards,

Jos (programming language lawyer par excellance ;-)

Not true, C++ currently does not allow automatic typing of variables. Maybe once the new auto keyword is added, but even then I am not sure if it can be used with parameters, only with assignment I believe.

[JosAH]

Not true, C++ currently does not allow automatic typing of variables. Maybe once the new auto keyword is added, but even then I am not sure if it can be used with parameters, only with assignment I believe.

Of course I was only talking about the body of that little rascal (see above). The
main() definition is all wrong of course and there are some include files missing
etc. etc. Good ol' K&R1 C would've loved the entire thing though ;-)

kind regards,

Jos

[r035198x]

The body of that ugly little thingy is still valid C++ ...

kind regards,

Jos (programming language lawyer par excellance ;-)

Won't that require auto typing?
P.S I really need to give my c++ more time these days

[JosAH]

Won't that require auto typing?
P.S I really need to give my c++ more time these days

No, I was assuming an:

int _= 1;
 

thingy just before the statements in that body; it doesn't matter much ;-)

kind regards,

Jos

[r035198x]

No, I was assuming an:

int _= 1;
 

thingy just before the statements in that body; it doesn't matter much ;-)

kind regards,

Jos

Of course.
B.T.W I can now see your avatar (or lack of it) on the leader board.

[weaknessforcats]

Check out Obfuscated C and Other Mysteries by Don Libes (Wiley & Sons 1993).

[JosAH]

Check out Obfuscated C and Other Mysteries by Don Libes (Wiley & Sons 1993).

Even better: check the IOCCC site (International Obfuscated C Code Contest);

that was so much fun in the K&R1 days. I think there's even an old entry from
my sick brain in there (I could be wrong though).

K&R1 C was the best language for those purposes. C++ has too many rules
for that and Java is a sissy language when it comes to obfuscation ;-)

kind regards,

Jos

edit: there! I found an old entry; it didn't make it as a winner though:

main(o,O0)char**O0;{int OO,O;O=--o?atoi(O0[!0]):!
0;for(o=((OO=O*O)-O+!0+!0)>>!0;OO;o+=((--OO%O)?-!
0:((((o-!0)%O)?O:0)+!0))-(((o-!0)%O)?O:0)){printf
("\n%*d "+!!(OO%O),!0<<!0<<!0,o+=(o<!0)?O*O:0);}}
 

It generates magic squares of odd size and it doesn't use any memory even
proportional to n (the odd number). Cute eh? ;-)

[JosAH]

Of course.
B.T.W I can now see your avatar (or lack of it) on the leader board.

So I noticed; btw what do you think of my fine avatar?

kind regards,

Jos;-)