Recently a friend of mine has given me a piece of code in C++:

puts(&3["abcdef"]);

At first glance it seems to not compile at all. But not only it compiles, but also prints “def”.

It’s an interesting example of “syntatic sugar“. In C++ synax tab[i] is an human-readable alias to *(tab+i). So following code:

	int tab[4];
	tab[3] = 17;
	printf("%d %d %d\n", tab[3], 3[tab], *(tab+3));

prints “17” three times.

Let’s go back to our code.

3["abcdef"]

means

*(3 +"abcdef")

so this expression returns “d”. But when we obtain memory adress of “d” using & operator, we can print string that starts at “d” using puts command.
So the code prints “def”.

For more interesting examples of code obsfuscation visit: www.ioccc.org or International Obfuscated C Code Contest.