var oneNumber = new[] {5};
var theOnlyNumber = oneNumber.SingleOrDefault();
Console.WriteLine(theOnlyNumber); //5
var numbers = new[] {1,2,3,4,5};
var theOnlyNumberSmallerThanTwo = numbers.SingleOrDefault(n => n < 2);
Console.WriteLine(theOnlyNumberSmallerThanTwo); //1
var theOnlyNegativeNumber = numbers.SingleOrDefault(n => n < 0);
Console.WriteLine(theOnlyNegativeNumber); //0
The following throws InvalidOperationException
:
var theOnlyNumberInNumbers = numbers.SingleOrDefault();