C# Language Any and First(OrDefault) - best practice


Example

I won't explain what Any and FirstOrDefault does because there are already two good example about them. See Any and First, FirstOrDefault, Last, LastOrDefault, Single, and SingleOrDefault for more information.

A pattern I often see in code which should be avoided is

if (myEnumerable.Any(t=>t.Foo == "Bob"))
{
    var myFoo = myEnumerable.First(t=>t.Foo == "Bob");
    //Do stuff
}

It could be written more efficiently like this

var myFoo = myEnumerable.FirstOrDefault(t=>t.Foo == "Bob");
if (myFoo != null)
{
    //Do stuff
}

By using the second example, the collection is searched only once and give the same result as the first one. The same idea can be applied to Single.