Please explain this code

Question

Please I saw this code on community challenge and I got curious so I run it on playground.
The correct answer on the challenge was 83 e but I got a different answer here (115 e).
Please who can explain this code bit
Thanks

https://code.sololearn.com/caeChPu6zEs4/?ref=app

Answer 1

Brian thanks
It'd be great if they add such tutorials here

Answer 2

0[arr] returns first element ‘s’ whose ascii value is 115. 2[arr+3] means 3rd character from ‘o’ i.e. ‘e’.

Answer 3

Chidera the array syntax 0[arr] and 2[arr+3] is an unconventional way of expressing the equivalent expressions arr[0] and arr[2+3].

Array expressions are composed of a memory address and an offset, like x[i], where x is the address and i is the offset. The offset i gets added to x to calculate the element address. The final element address is x+i.

Because addition is commutative, you get the same address result whether you add x+i or i+x.

Therefore, both x[i] and i[x] are the same. The latter, i[x], tells C to start with address i (which is really an index) and add offset of x (which is really an address).

[EDIT: Remember that this is pointer arithmetic so, when adding the offset, it adds offset*(sizeof <type>).]

Answer 4

Pąľľąvī thanks but still confused 😐

Answer 5

Why is the array arr used like this 0[arr] and 2[arr+3]?

Answer 6

Thanks Pąľľąvī and Flash