List<string> SampleList = new List<string>();
string tmpStr = "MyStringValue";
From this example, how to check the value of the string variable tmpStr if it's already in SampleList?
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But I voted up for both of you! Thanks!Chris N.P.– Chris N.P.2013-09-12 02:41:17 +00:00Commented Sep 12, 2013 at 2:41
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2 Answers
You could use the List<T>.Contains Method
if (SampleList.Contains(tmpStr))
{
// list already contains this value
}
else
{
// the list does not already contain this value
}
If your objective is to prevent your list from containing duplicate elements at all times then you might consider using the HashSet<T> Class which does not allow for duplicate values.
8 Comments
Chris N.P.
Oh ".Contains" is the key then. Thank you. I'm, totally new to List object.
Chris N.P.
Can you give me an example on how to use this HashSet<T> Class to my List?
User 12345678
@ChrisN.P. Here is a link to a comprehensive (much more so than I could be) beginners' tutorial: dotnetperls.com/hashset
Chris N.P.
Thanks. Let me check this then :)
Chris N.P.
Alright I decided to select your's for posting your solution first. ;)
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Any particular reason for using List?
You can use a Set, Set<string> hs = new HashSet<string>(); and it will not allow duplicates.
Set<string> hs = new HashSet<string>();
hs.add("String1");
hs.add("String2");
hs.add("String3");
// Now if you try to add String1 again, it wont add, but return false.
hs.add("String1");
If you do not want duplicates for case insensitive elements use
HashSet<string> hs = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
Hope that helps.
10 Comments
Chris N.P.
I used List to store all the items from the database.
Chris N.P.
Can I apply this approach to a List?
JNL
@ChrisN.P. With approach do you mean by not allowing duplicates?
Chris N.P.
Yes the one that you posted.
JNL
Set will be useful if you do not want duplicates. HashMap will be useful if you need to associate key-value pairs, for example, say String, and the occurrence of the String in the database. So it all depends on your use.
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