The code is clearly written by someone who knows C first. If I was given that to review I would reject it.

Using NULL, inconsistent indenting, putting int i outside the for loop, struct's that should be a class and a class that has no reason being a class. Not to mention variables like 'o'* and a class named Obj (woo saved 3 letters and named it the most generic thing I could think of). one struct starts with a _ the other does not... using printf rather then cout. Bad variable naming in general.

And this is all before even reporting the real issues which from the looks of it are more with the c code then the c++ code.

* o does not stand for object, but objects making it an even worse sin