CODEWITHSUNDEEP
c#listperformance
manemawanna
manemawanna

Reputation: 543

Quicker ways to search a C# List<String> for substrings

I currently have a list called regkey and a string called line_to_delete, which I obviously want to delete from the list. At the moment I'm searching through one element of the list at a time creating substrings as line_to_delete only represents part of the line that I want to delete but is uniquely identifiable within the list.

Anyway what I really need to do is make this more efficient, use fewer resources and be quicker, so are there any ways to do this?

Upvotes: 5

Views: 13662

Answers (5)

Rohit Gupta
Rohit Gupta

Reputation: 624

I think it is better to use indexOf rather than contains, that speeds up search

so use :

regkey.RemoveAll(k => k.IndexOf(line_to_delete) >=0);

Upvotes: 2

Michael G
Michael G

Reputation: 6755

        List<String> regKey = new List<String> { "test1", "test2" };
        var toDelete = regKey.Where(u => u.Contains(line_to_delete)).SingleOrDefault();
        if (toDelete != null)
            regKey.Remove(toDelete);

or

regkey.RemoveAll(k => k.Contains(line_to_delete));

This will make your deletion more readable, but I'm not sure on the performance compared against your current method.

Upvotes: 2

mfeingold
mfeingold

Reputation: 7134

Your best bet is to sort the list and use binary search. SortedList will do this for you.. This way you can get O(log(n)) performance

Upvotes: 3

Jamie Ide
Jamie Ide

Reputation: 49301

Use lamba expressions if it's a List<string>:

list.RemoveAll(x => x.Contains(line_to_delete));

Upvotes: 6

Konrad Rudolph
Konrad Rudolph

Reputation: 546083

The simplest way is to use:

var result = list.Where(x => !x.Contains(line_to_delete))

First, make sure this isn’t efficient enough. If it isn’t, you need to resort to advanced data structures to represent your strings, such as a trie. There’s no native support in C# for any such things.

Upvotes: 2

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