How to compare string to String Array in C#?

Question

I have an string;

String uA = "Mozilla/5.0 (iPad; CPU OS 8_2 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Mobile/12D508 Twitter for iPhone";

String[] a= {"iphone","ipad","ipod"};

It must return ipad because ipad is in the first match ipad at the string. In other case

String uA = "Mozilla/5.0 (iPhone/iPad; CPU OS 8_2 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Mobile/12D508";

Same string array first match to iPhone.

Answer 1

So you want the word within the array which occurs earliest in the target string? That sounds like you might want something like:

return array.Select(word => new { word, index = target.IndexOf(word) })
            .Where(pair => pair.index != -1)
            .OrderBy(pair => pair.index)
            .Select(pair => pair.word)
            .FirstOrDefault();

Those steps in detail:

• Project the words into a sequence of word/index pairs, where the index is the index of that word within the target string
• Omit words that didn't occur in the target string by removing pairs where the index is -1 (string.IndexOf returns -1 if it's not found)
• Order by index to make the earliest word occur as the first pair
• Select the word within each pair, as we no longer care about indexes
• Return the first word, or null if the sequence is empty

Answer 2

Try this:

 String uA = "Mozilla/5.0 (iPad; CPU OS 8_2 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Mobile/12D508 Twitter for iPhone";

 String[] a = { "iphone", "ipad", "ipod" };

 var result = a.Select(i => new { item = i, index = uA.IndexOf(i) })
               .Where(i=>i.index >= 0)
               .OrderBy(i=>i.index)
               .First()
               .item;

Answer 3

here is a none linq method to do that,

    static string GetFirstMatch(String uA, String[] a)
    {
        int startMatchIndex = -1;
        string firstMatch = "";
        foreach (string s in a)
        {
            int index = uA.ToLower().IndexOf(s.ToLower());
            if (index == -1)
                continue;
            else if (startMatchIndex == -1)
            {
                startMatchIndex = index;
                firstMatch = s;
            }
            else if (startMatchIndex > index)
            {
                startMatchIndex = index;
                firstMatch = s;
            }
        }
        return firstMatch;
    }