Is chars[4] and 4[chars] the same in C? Why?

Question

I've read this and don't believe it :) I've no compiler here to test.

Answer 1

Because a[b] is exactly the same as *(a+b), and + is commutatitve.

chars[4] is *(chars+4), and 4[chars] is *(4+chars)

Answer 2

http://c-faq.com/aryptr/joke.html Try this to test compile: http://codepad.org/

Answer 3

In raw C, the [] notation is just a pointer math helper. Before [], you'd look for the fourth char in the block pointed to by ptr like:

*(ptr+4)

Then, they introduced a shortcut which looked better:

ptr[4]

Which transaltes to the earlier expression. But, if you'd write it like:

4[ptr]

This would translate to:

*(4+ptr)

Which is indeed the same thing.