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I have been asked a question that is a little ambiguous for my coursework.
The array of strings is regarded as a set, i.e. unordered.
I'm not sure whether I need to remove duplicates from this array?
I've tried googling but one place will tell me something different to the next. Any help would be appreciated.
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"A set has no duplicate elements. An element is either a member of a set or not. It cannot be in the set twice."
From what I've read (I'm no mathematician), a set can have identical elements within it when it is defined, but when working with sets or comparing sets, the duplicates are ignored. So {1, 1, 2} is the same as {1, 2} is the same as {2, 1}. A multiset is where multiple instances of an element matters.
Set is not allowed to store duplicated values by definition. If you need duplicated values, use a List. As specified on the documentation of the interface, when you try to add a duplicated value, the method add returns false, not an Exception.
The meaning of "sets do not allow duplicate values" is that when you add a duplicate to a set, the duplicate is ignored, and the set remains unchanged. This does not lead to compile or runtime errors: duplicates are silently ignored. Set is implemented like that to avoid duplication.
From Wikipedia in Set (Mathematics)
A set is a collection of well defined and distinct objects.
Perhaps the confusion derives from the fact that a set does not depend on the way its elements are displayed. A set remains the same if its elements are allegedly repeated or rearranged.
As such, the programming languages I know would not put an element into a set if the element already belongs to it, or they would replace it if it already exists, but would never allow a duplication.
Programming Language Examples
Let me offer a few examples in different programming languages.
In Python
A set in Python is defined as "an unordered collection of unique elements". And if you declare a set like a = {1,2,2,3,4} it will only add 2 once to the set.
If you do print(a) the output will be {1,2,3,4}.
Haskell
In Haskell the insert operation of sets is defined as: "[...] if the set already contains an element equal to the given value, it is replaced with the new value."
As such, if you do this: let a = fromList([1,2,2,3,4]), if you print a to the main ouput it would render [1,2,3,4].
Java
In Java sets are defined as: "a collection that contains no duplicate elements.". Its add operation is defined as: "adds the specified element to this set if it is not already present [...] If this set already contains the element, the call leaves the set unchanged".
Set<Integer> myInts = new HashSet<>(asList(1,2,2,3,4));
System.out.println(myInts);
This code, as in the other examples, would ouput [1,2,3,4].
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