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Displaying Free Array Elements [TOC]
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Extend the info function to also display the unused/available array elements.
After displaying the elements on the stack, print a vertical bar followed by
the available array elements.

For example, the operations `push(3)`, `push(4)`, and then `pop()` should
result in the following output:

---- CODE(type=txt) ------------------------------------------------------------
MCL:tmp lehn$ ./a.out 
top = 3
stack: [3] | [0] [0] [0] [0] 
top = 4
stack: [3] [4] | [0] [0] [0] 
top = 3
stack: [3] | [4] [0] [0] [0] 
--------------------------------------------------------------------------------

This output clearly demonstrates that during a pop operation, an array element
is not "deleted" or overwritten; only the stack pointer is decremented.

Keep the following in mind: In the program, `stack` is defined as an array with
a dimension of `5`. If this dimension is changed (for example, to `10`), it
should not be necessary to modify the `info` function. The info function should
automatically adapt to the new dimension of the `stack` array and remain
functional.