Ok, I see where you are going with this. I used to use $[ like that too, but it's both hard to read and unnecessary unless you alter it somewhere else. So if you don't touch $[ anywhere, there is no reason not to use 0. Besides, its somewhat deprecated.

As for $#, that has to do with formatting print statements... not array boundaries, unless of course, you meant $#arrayName which is the index of the last element of the specified array and certainly not deprecated. In fact, not only does it give you the last index, but you can use it as an lvalue to change the size of an array.

(And yes, the use of $# by itself to alter the formatting of print statements is highly deprecated and should not be used.)