The Enumerable.Sum
extension method calculates the sum of numeric values.
In case the collection's elements are themselves numbers, you can calculate the sum directly.
int[] numbers = new int[] { 1, 4, 6 };
Console.WriteLine( numbers.Sum() ); //outputs 11
In case the type of the elements is a complex type, you can use a lambda expression to specify the value that should be calculated:
var totalMonthlySalary = employees.Sum( employee => employee.MonthlySalary );
Sum extension method can calculate with the following types:
In case your collection contains nullable types, you can use the null-coalescing operator to set a default value for null elements:
int?[] numbers = new int?[] { 1, null, 6 };
Console.WriteLine( numbers.Sum( number => number ?? 0 ) ); //outputs 7