When to use .First and when to use .FirstOrDefault with LINQ?

Question

I\'ve searched around and haven\'t really found a clear answer as to when you\'d want to use .First and when you\'d want to use .FirstOrDefault wit

Answer 1

This type of the function belongs to element operators. Some useful element operators are defined below.

1. First/FirstOrDefault
2. Last/LastOrDefault
3. Single/SingleOrDefault

We use element operators when we need to select a single element from a sequence based on a certain condition. Here is an example.

  List items = new List() { 8, 5, 2, 4, 2, 6, 9, 2, 10 };

First() operator returns the first element of a sequence after satisfied the condition. If no element is found then it will throw an exception.

int result = items.Where(item => item == 2).First();

FirstOrDefault() operator returns the first element of a sequence after satisfied the condition. If no element is found then it will return default value of that type.

int result1 = items.Where(item => item == 2).FirstOrDefault();