Linq query a string array in c# if contains either of two values?

Question

I have an array of strings

string[] tmp = foo();

If NONE of the strings in foo contain either "bar" or "baz" I want to execute some code. Is this the proper way to query this object?

if(!tmp.Any(p => p.ToLower().Contains("bar") || p.ToLower().Contains("baz"))
 doSomething();

The || seems silly. Should I be using a regular expression here or is there an even better way to be doing this? ***Also note the values in tmp are like "bar=someValue" like a query string. This code works ok but I'm certain it can written better. Thanks for any tips of feedback.

Why does the || seem silly? You want to do something if either X or Y is true for any item. Seems entirely reasonable to me. — Jon Skeet
– Jon Skeet, Commented Nov 14, 2012 at 15:46
To me you code looks perfectly alright. If there are many items, I would create extension method to simplify the syntax. For upto 2/3 items I would go with this approach. — Tilak
– Tilak, Commented Nov 14, 2012 at 15:52
Yes Jon || is ok now, but what about when I need to look for more values beside bar or baz? I was looking for something that scales a little better. I like the intersection approaches but the values in tmp are in name=value format. Thanks! — Hcabnettek
– Hcabnettek, Commented Nov 14, 2012 at 15:54
This doesn't exactly answer your question, but it's actually faster to use p.IndexOf("bar", StringComparison.CurrentCultureIgnoreCase) < 0 and avoid the ToLower() call. — user27414
– user27414, Commented Nov 14, 2012 at 15:58
"This code works ok but I'm certain it can written better." -- to what end? Without knowing in what way something is inadequate, it is impossible to improve it. — user27414
– user27414, Commented Nov 14, 2012 at 16:02

L.B · Accepted Answer · 2012-11-14 16:04:04Z

4

Any better? I don't know but should work.

if(!tmp.Select(x => x.Split('=')[0])
                    .Intersect(new[] { "foo", "baz" }, 
                               StringComparer.InvariantCultureIgnoreCase).Any())
    doSomething();

edited Nov 14, 2012 at 16:04

answered Nov 14, 2012 at 15:44

L.B

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5 Comments

Asif Mushtaq Over a year ago

but he also says that the strings are in form "bar=someValue".

Hcabnettek Over a year ago

yes the code works as is, it just seems inefficient is all. I was thinking of this perhaps? !tmp.Any(p => Regex.IsMatch(p, @"^(foo|baz)")

Asif Mushtaq Over a year ago

Yes, its right now, but can you please explain that how it is better then tmp.Any(p => p.ToLower().Contains("bar") || p.ToLower().Contains("baz"))

Rawling Over a year ago

Think you might be missing a !.

Asif Mushtaq Over a year ago

The existing one seems at least more elegant.

Joshua Honig · Accepted Answer · 2012-11-14 16:21:51Z

You can use nested Any with StringComparison overload of IndexOf:

string[] source = { "hi=there", "hello=world", "foo=bar" };
string[] exclude = { "baz", "bar" };

if (!source.Any(src => 
        exclude.Any(exl =>  
            src.IndexOf(exl, StringComparison.InvariantCultureIgnoreCase) >= 0))) 
    doSomething();

Or packaged as an extension method:

public static class StringExtensions {
    public static bool ContainsAny(
        this IEnumerable<string> source,
        IEnumerable<string> target,
        StringComparison comparisonType = StringComparison.InvariantCultureIgnoreCase) {
        return source.Any(xsource => target.Any(
                xtarget => xsource.IndexOf(xtarget, comparisonType) >= 0));
    }
}


// Later ...
if (!source.ContainsAny(exclude))
    doSomething();

Eren Ersönmez · Accepted Answer · 2012-11-14 16:26:09Z

1

I don't think there is anything wrong with your existing code; though it could be slightly modified to avoid an extra ToLower() call:

var exists = tmp.Any(p => 
{ 
    var s = p.ToLower(); 
    return s.Contains("bar") || s.Contains("baz");
});
if(!exists) doSomething();

If your search terms can be numerous, something like this might work better:

var terms = new string[] {"bar", "baz", "foo", "boo", ...};
var exists = tmp.Any(p => terms.Any(t => p.ToLower().Contains(t)));
if(!exists) doSomething();

answered Nov 14, 2012 at 16:26

Eren Ersönmez

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