Check if a string contains an element from a list (of strings)

For the following block of code:

For I = 0 To listOfStrings.Count - 1
    If myString.Contains(lstOfStrings.Item(I)) Then
        Return True
    End If
Next
Return False

The output is:

Case 1:

myString: C:\Files\myfile.doc
listOfString: C:\Files\, C:\Files2\
Result: True

Case 2:

myString: C:\Files3\myfile.doc
listOfString: C:\Files\, C:\Files2\
Result: False

The list (listOfStrings) may contain several items (minimum 20) and it has to be checked against a thousands of strings (like myString).

Is there a better (more efficient) way to write this code?

With LINQ, and using C# (I don't know VB much these days):

bool b = listOfStrings.Any(s=>myString.Contains(s));

or (shorter and more efficient, but arguably less clear):

bool b = listOfStrings.Any(myString.Contains);

If you were testing equality, it would be worth looking at HashSet etc, but this won't help with partial matches unless you split it into fragments and add an order of complexity.

update: if you really mean "StartsWith", then you could sort the list and place it into an array ; then use Array.BinarySearch to find each item - check by lookup to see if it is a full or partial match.

when you construct yours strings it should be like this

bool inact = new string[] { "SUSPENDARE", "DIZOLVARE" }.Any(s=>stare.Contains(s));

There were a number of suggestions from an earlier similar question "Best way to test for existing string against a large list of comparables".

Regex might be sufficient for your requirement. The expression would be a concatenation of all the candidate substrings, with an OR "|" operator between them. Of course, you'll have to watch out for unescaped characters when building the expression, or a failure to compile it because of complexity or size limitations.

Another way to do this would be to construct a trie data structure to represent all the candidate substrings (this may somewhat duplicate what the regex matcher is doing). As you step through each character in the test string, you would create a new pointer to the root of the trie, and advance existing pointers to the appropriate child (if any). You get a match when any pointer reaches a leaf.

I liked Marc's answer, but needed the Contains matching to be CaSe InSenSiTiVe.

This was the solution:

bool b = listOfStrings.Any(s => myString.IndexOf(s, StringComparison.OrdinalIgnoreCase) >= 0))

Old question. But since VB.NET was the original requirement. Using the same values of the accepted answer:

listOfStrings.Any(Function(s) myString.Contains(s))

Check if a string contains an element from a list (of strings)

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