How to identify multiple occurrence of a record in string array

Question

I have one string[] and its has only 4 possible values like "www", "xxx", "yyy" and "zzz".

In a request to my application different combinations of values came in this string[], like:

Case 1: Single value multiple time:

string[] a = {"xxx", "xxx", "xxx"}; //only "xxx" is present in array multiple times

Case 2: Multiple values single time:

string[] a = {"xxx", "zzz", "yyy"}; //only single value is present for "xxx", "zzz" and "yyy"

Case 3: Multiple values multiple times:

string[] a = {"xxx", "zzz", "xxx", "yyy", "zzz"}; //"xxx" and "zzz" are present multiple times

Now, what could be the best possible way to find out that only a single value in coming multiple time or multiple values are coming either single or multiple time?

bytefire · Accepted Answer · 2014-06-12 14:34:37Z

2

You can use something like this:

int count = a.Distinct().Count();

And then compare count with total values in the array, i.e. a.Length. If they are same then every value is repeated once.

count contains the number of time a unique value appears in the array.

Using HashSet

int count = new HashSet<string>(a).Count;

However the first approach is recommended.

edited Jun 12, 2014 at 14:34

answered Jun 12, 2014 at 11:29

bytefire

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3 Comments

Geeky Ninja Over a year ago

Is it possible to this with Hashset<>?

bytefire Over a year ago

@Ryan yes and that was my first thought. But it might be overkill if all that is needed is a check for duplicates.

Geeky Ninja Over a year ago

@ bytefire yes you are right first approach is better than hashset<> for this scenario.

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