What is the difference between SingleOrDefault() and FirstOrDefault() methods?

Both SingleOrDefault() and FirstOrDefault() LINQ methods return default value of the passed collection data type when there are no matching elements found for the condition predicate.
Both methods return only one record from the collection that matches the predicate.
SingleOrDefault() expects the condition predicate to match only one record in the set - for example, a postUrl in a collection of BlogPost objects. If there are more than one objects that match the predicate, SingleOrDefault() method throws exception.
Whereas the FirstOrDefault() method returns the first object in the collection that matches the prerequisite and so no such exception is thrown.

Ram
February 22, 2021
Interview Q&A

Both SingleOrDefault() and FirstOrDefault() LINQ methods return default value of the passed collection data type when there are no matching elements found for the condition predicate.
Both methods return only one record from the collection that matches the predicate.
SingleOrDefault() expects the condition predicate to match only one record in the set – for example, a postUrl in a collection of BlogPost objects. If there are more than one objects that match the predicate, SingleOrDefault() method throws exception.
Whereas the FirstOrDefault() method returns the first object in the collection that matches the prerequisite and so no such exception is thrown.

Ram

I'm a full-stack developer and a software enthusiast who likes to play around with cloud and tech stack out of curiosity. You can connect with me on Medium, Twitter or LinkedIn.