LINQ Where and FirstOrDefault

string[] s = new string[] {"cc", "aa", "bb", "" };
string result = s.FirstOrDefault(开发者_如何转开发x => x.Equals("aa"));

Would one prefer the code above without the .Where() statement or with it?

string[] s = new string[] {"cc", "aa", "bb", "" };
string result = s.Where(x => x.Equals("aa")).FirstOrDefault();

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Both forms are equivalent, use the one you prefer. I don't think it makes a big difference in terms of performance... I tend to chose the first form, because it's shorter.

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You should really study IQueryable object, it does not work in order you specify. The query is rather optimized by LINQ. There are a lot of tools to scan the result query like LINQPad and others.

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It depends on the agreement on the coding (code formatting agreement). And no matters for personal use.