The depth is 32 bit, not the index into the file.

If you are nesting 2 Billion times in a row ( at minimum this means repeat { 2 billion times followed by a value before } another 2 billion times. You have messed up.

You have 4GB of "padding"...at minimum.

You file is going to be Petabytes in size for this to make any sense.

You are using a terrible format for whatever you are doing.

You are going to need a completely custom parser because nothing will fit in memory. I don't care how much RAM you have.

Simply accessing an element means traversing a nested object 2 billion times in probably any parser in the world is going to take somewhere between minutes and weeks per access.

All that is going to happen in this program is a crash.

I appreciate that people want to have some pointless if(depth > 0) check everywhere, but if your depth is anywhere north of million in any real world program, something messed up a long long time ago, never mind waiting until it hits 2 billion.