Question:
When I need to check whether a collection has elements or not, which of the two methods will be faster, .Count() =! 0 or .Any() ?
I've heard that .Count() can be faster in some cases. But checking the source code , the Any() method seemed better to use.
There is also the possibility of having a condition inside the method, in which case you can change which of the two is faster?
And when it is used in a DbSet , the query generated by .Any() is different from .Count() I imagine. But when it comes to performance, is Any() still ahead?
Answer:
It depends on the type of enumeration.
If it is based on ICollection<T> , .Count (property, not method) is faster because the value is already .Count inside the structure (optimized)..Any() requires using the sequence GetEnumerator() / MoveNext() / Dispose() .
In any other enumerations,.Count() (now method) iterates over all elements. Any() stops flowing when finding the first string, so it's faster than .Count()
In summary, Any() behaves better in most cases.