What does FirstOrDefault mean in C#?

the first element of a sequence
FirstOrDefault(IEnumerable) Returns the first element of a sequence, or a default value if the sequence contains no elements.

What is difference between first and FirstOrDefault in Linq?

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() will return the default value (null) if there is no result data. First() will throw an exception if there is no result data, as you can see below.

What is FirstOrDefault?

FirstOrDefault. Returns the first element of a collection, or the first element that satisfies a condition. Returns a default value if index is out of range. First and FirstOrDefault has two overload methods. The first overload method doesn’t take any input parameter and returns the first element in the collection.

Why do we use FirstOrDefault in C#?

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 Entity Framework FirstOrDefault?

First or FirstOrDefault is used when you expect more than one record in the database. This method returns the first matching row from the database. If no records found in the database then First will throw an exception, while FirstOrDefault returns the default value.

Does FirstOrDefault execute query?

All standard Linq operators, which return single, non-enumerable result, are executed immediately at the point where query is declared. So, FirstOrDefault , Count , Sum and other operators which return single value are executed immediately.

Which is faster any or FirstOrDefault?

Although it has similar implementation, I believe Any is a bit faster because it doesn’t have to return an object, which in some cases may be rich, with state and behavior, depends on how well the query is thought out.

Which collection is faster in C#?

ListDictionary is faster than Hashtable for small collections (10 items or fewer). The Dictionary generic class provides faster lookup than the SortedDictionary generic class.

Is HashSet faster than set?

Performance. Simply put, HashSet is faster than the TreeSet. HashSet provides constant-time performance for most operations like add(), remove() and contains(), versus the log(n) time offered by the TreeSet. Usually, we can see that the execution time for adding elements into TreeSet is much more than for the HashSet.