To C or not to C
That's here the question.

In other languages regulations are often very strict. For example: Don't access array elements with indices exceeding the range. But what if I just WANT to do this? If I decide to do it, the computer has to obey. I hate languages that complain "No. No. Don't do this. Bad things may happen...". C doesn't complain. A C compiler knows that you are intelligent and have good reasons whenever you break the rules of old-fashioned programming style.

Due to the range of possibilities that you have in C solutions of problems tend to be very short.
Imagine you want to print the sequence of the integers from a to b.
If a<b then the sequence is to be printed in ascending order and if a>b then it is to be printed in descending order.
A solution in a Pascal-style language could look like this:

IF a<b THEN
  FOR i:=a TO b DO writeln(i)
ELSE
  FOR i:=a DOWNTO b DO writeln(i);

but in C it can be simply written as

for(i=a;printf("%d\n",i),d=b-i;i+=(d|1)%2);	

The C notation may confuse you but this is because you still think in a human language. Try to think like a computer!

1. You initialize i with i=a.
2. Print i. This can't be wrong.
3. Compute the difference to your goal: d=b-i
   C now interprets the result as a condition. If d is zero, 
   then the for-loop is exited.
4. Now notice that the expression (d|1)%2 yields +1 if d is greater than zero
   and -1 if d is less than zero. 
   So add (d|1)%2 to your current i for the next iteration.

November 30, 1995
Mark Dettinger

Here's a comment by Leigh Lundin from Infinite Space Systems.

P.S. :
Don't take it too serious. In reality I wouldn't write code like this. In the ACM Southwestern Programming Contest 1996 me and my team used C. To avoid bugs we tried to keep the code as pretty as possible and we compiled our programs with gcc -ansi -Wall -pedantic to get every warning message you can think of. As the ranklist shows you, this strategy works.