Checking if a value is in an array and then using that value

Question

I have a method which recieves an array of strings from another method. This array contains several strings, for days, moviegenres etc. I need to check if the array contains any of the moviegenres, and if so I need that specific value.

here is what I have now:

if (eventsSelected.Contains("act") ||
               eventsSelected.Contains("adv") ||
               eventsSelected.Contains("ani") ||
               eventsSelected.Contains("doc") ||
               eventsSelected.Contains("dra") ||
               eventsSelected.Contains("hor") ||
               eventsSelected.Contains("mys") ||
               eventsSelected.Contains("rom") ||
               eventsSelected.Contains("sci") ||
               eventsSelected.Contains("thr"))
            {
                //get the value that is in the array contains.
            }

Because my code checks for 10 different values how can I find out which value is true?

So let's say the array contains the value "act" how can I get that specific value?

Yuriy Faktorovich · Accepted Answer · 2017-01-05 16:06:52Z

3

foreach(var match in new [] {"act", "adv"}.Where(eventsSelected.Contains))
{
    //do stuff
}

Or if you just need the first one

var match = Array.Find(new[] { "act", "adv" }, eventsSelected.Contains);
if (!string.IsNullOrEmpty(match))
{
    // If you just want the first match
}

The match field contains the token you were searching on, so act or adv.

edited Jan 5, 2017 at 16:06

answered Jan 5, 2017 at 15:57

Yuriy Faktorovich

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Comments

Tim Schmelter · Accepted Answer · 2017-01-05 15:56:53Z

3

Either use multiple if or use a string[] and Array.FindIndex:

string[] tokens = {"adv", "ani", "doc" .... };
int index = Array.FindIndex(tokens, t => eventsSelected.Contains(t));
if(index >= 0)
{
     Console.WriteLine("First value found was: " + tokens[index])
}

answered Jan 5, 2017 at 15:56

Tim Schmelter

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2 Comments

Yuriy Faktorovich Over a year ago

If you wanna use the static Array methods, you can use the Array.Find, since the index value is never really used.

Tim Schmelter Over a year ago

@YuriyFaktorovich: well, it has one advantage, you can use Array.FindIndex(array, startIndex, predicate) if you want to find the next match. You just need to pass ++index.

Patrick Hofman · Accepted Answer · 2017-01-05 15:59:56Z

0

You can use Intersect

var values = new[] {"act", "adv", "ani", etc};
var matches = values.Intersect(eventsSelected);

//matches contains all matching values

edited Jan 5, 2017 at 15:59

Patrick Hofman

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answered Jan 5, 2017 at 15:59

Andy Nichols

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4 Comments

Patrick Hofman Over a year ago

This does an equality comparison, not a Contains like OP does.

Andy Nichols Over a year ago

@PatrickHofman Actually, I'm not sure it does. If eventsSelected is an array (and the name suggests it is), then Contains is testing equality for each element of the array.

Patrick Hofman Over a year ago

Agreed. Code is ambiguous.

Joshua Volkers Over a year ago

eventsSelected is indeed an array, I realise I should have made that more clear.

chambo · Accepted Answer · 2017-01-05 16:05:33Z

0

Similar to the answer from Tim, but using LINQ rather than Array functions:

string[] tokens = {"adv", "ani", "doc" .... };
string firstMatch = eventsSelected.FirstOrDefault(s => tokens.Contains(s));
if (firstMatch != null)
{
    // Do something with firstMatch
}

answered Jan 5, 2017 at 16:05

chambo

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Comments

Dunno · Accepted Answer · 2017-01-05 16:09:44Z

0

I couldn't help but notice that you've written your tokens in sorted order so just for the fun of it you could do:

string[] sortedTokens = {"act", "adv", "ani", ... };
int index = Array.FindIndex(eventsSelected, e => Array.BinSearch(sortedTokens, e) > 0)

And then proceed as in Tim's answer, except that this time, index is the index from eventsSelected. This gives you O(nlog(k)) time complexity, where n is the size of eventsSelected and k is the size of tokens (other answers give O(nk), not that it matters much).

answered Jan 5, 2017 at 16:09

Dunno

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