Comparing strings with linq

Question

I am comparing strings with .Contains() but I found a problem:

foreach (var pair in cluster)
{
    if (pair.Key.Contains("a" + i.ToString()))
    {
         vlr = pair.Value;
    }
}

"a10", "a11", "a1.." are retrieving when I search "a1". There is another way to compare diferente of ==

I forgot! using contais: pair.key is ("a5-a6", "a1-a8", "a10-a7") and the error occours when I need to find "a1".... The code must retrieve only "a1-a8" and not "a1-a8" and "a10-a7". I guess I have to splitted .Split('-') and compare both results separated... — user1801745
– user1801745, Commented May 23, 2013 at 2:41
It would be more helpful if you edited your question with that detail rather than burying it in a comment. — D Stanley
– D Stanley, Commented May 23, 2013 at 2:50

D Stanley · Accepted Answer · 2013-05-23 02:49:22Z

1

Based on your comment I think the query you're looking for is:

var query = cluster.Where(kvp => kvp.Key
                                    .Split('-')
                                    .Contains("a" + i.ToString())  // Array.Contains, not String.Contains
                         )
                   .Select(kvp => kvp.Value);

answered May 23, 2013 at 2:49

D Stanley

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Comments

Sergey Kalinichenko · Accepted Answer · 2013-05-23 02:55:30Z

If you would like to make sure that your search string is an isolated substring, not a prefix or a suffix of a larger substring, you can use regular expressions. For example, to see if a string contains a5 but not a52 or xa5, you can do this:

if (Regex.Matches(input, "\\ba5\\b").Count > 0) ...

Here is an example:

Console.WriteLine(Regex.Matches("hello a5 world", "\\ba5\\b").Count > 0);  // True
Console.WriteLine(Regex.Matches("hello a55 world", "\\ba5\\b").Count > 0); // False
Console.WriteLine(Regex.Matches("hello xa5 world", "\\ba5\\b").Count > 0); // False

Here is a demo on ideone.

Regex is versatile enough to let you adjust the expression to your needs: you can use positive and negative lookahead/lookbehind. For example, if you need to make sure that 5 is not followed by another digit, you can write "a5(?!\\d)".

COLD TOLD · Accepted Answer · 2013-05-23 02:30:35Z

0

.Contains() checks if the string contains a sub string in it or string

if you trying to see if they are equal or not you should use somethink like

if (pair.Key.Equals(i.ToString()))

or

string.Compare(pair.Key, i.ToString()) == 0

answered May 23, 2013 at 2:30

COLD TOLD

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