What is LastOrDefault in Linq C#?
In LINQ, LastOrDefault() method/operator is used to return the last element from the list/collection, and it’s same as LINQ Last() method, but only the difference is it will return the default value in case if the list/collection contains no element.
How do I get LastOrDefault in C#?
Use the LastorDefault() method to return the last element of a sequence or a default value if element isn’t there. The following is our empty list. List val = new List { };
What does LastOrDefault return?
LastOrDefault(IEnumerable) Returns the last element of a sequence, or a default value if the sequence contains no elements.
How do I use FirstorDefault?
Use the FirstorDefault() method to return the first element of a sequence or a default value if element isn’t there. List val = new List { }; Now, we cannot display the first element, since it is an empty collection. For that, use the FirstorDefault() method to display the default value.
What is difference between last and LastOrDefault in Linq?
Both Last() and LastOrDefault() will fetch the last occurrence of a value. But the major difference between Last() and LastOrDefault() is that Last() will throw an exception if there is no result data for the supplied criteria whereas LastOrDefault() will return the default value (null) if there is no result data.
What is Tolist C#?
This extension method converts collections (IEnumerables) to List instances. It is fast and easy-to-remember. It returns a List instance with the appropriate elements.
What is the difference between first and FirstOrDefault?
The major difference between First and FirstOrDefault is that First() will throw an exception if there is no result data for the supplied criteria whereas FirstOrDefault() returns a default value (null) if there is no result data.
What does ToList () do in Linq?
LINQ ToList() Method In LINQ, the ToList operator takes the element from the given source, and it returns a new List. So, in this case, input would be converted to type List.
What is the difference between ToList and ToArray C#?
In the majority of scenarios ToArray will allocate more memory than ToList . Both use arrays for storage, but ToList has a more flexible constraint. It needs the array to be at least as large as the number of elements in the collection. If the array is larger, that is not a problem.
Does ToList create a copy?
ToList() makes a shallow copy. The references are copied, but the new references still point to the same instances as the original references point to.
Is ToArray faster than ToList?
If you want additional capabilities of adding and removing from the collection later on without much hassle, then do a ToList (not really that you cant add to an array, but that’s not the right tool for it usually). In my own tests a while ago, I had found ToArray faster.
When should I call ToList?
Use ToList before you exit the using block that holds your DataContext . Return a query when the caller is likely/obligated to supply additional filtering criteria which will be used by indexes to reduce # of result rows and/or database IO.
What is difference between select and SelectMany in Linq?
Select is used to select value from a collection whereas SelectMany is used to select values from a collection of collection i.e. nested collection. Select and SelectMany both are projection operators.
Is FirstOrDefault faster than first?
First() and FirstOrDefault() are faster than Single() and SingleOrDefault() because First find the first() match only whereas Single() search element in a whole collection of elements.