C# – LINQ Sum Examples - CSharp Academy

Sum is a LINQ functionality which calculates total number of numeric items of a collection. In this article you can find examples of usage with list of primitive types (in our case integers) and also list of complex types.

List of integers

var items = new List<int>() { 1, 2, 3, 4, 5 };

1	var items = new List<int>() { 1, 2, 3, 4, 5 };

Total number can be calculated by calling Sum function without any arguments. It just adds up all figures.

var total = items.Sum(); // total = 15

1	var total = items.Sum(); // total = 15

List of objects

For the purpose of the article we need to create example class called Fruit containing two properties: Name and Price.

public class Fruit<br />
{<br />
    public string Name { get; set; }<br />
    public decimal Price { get; set; }<br />
}

public class Fruit

{

public string Name { get; set; }

public decimal Price { get; set; }

}

Now let’s create a list of fruits.

var fruits = new List<Fruit>()<br />
{<br />
    new Fruit() { Name = “Orange”, Price = 4.5M },<br />
    new Fruit() { Name = “Pear”, Price = 2.9M },<br />
    new Fruit() { Name = “Apple”, Price = 1.8M },<br />
    new Fruit() { Name = “Lemon”, Price = 2.1M },<br />
    new Fruit() { Name = “Banana”, Price = 2.7M }<br />
};

var fruits = new List<Fruit>()

{

new Fruit() { Name = “Orange”, Price = 4.5M },

new Fruit() { Name = “Pear”, Price = 2.9M },

new Fruit() { Name = “Apple”, Price = 1.8M },

new Fruit() { Name = “Lemon”, Price = 2.1M },

new Fruit() { Name = “Banana”, Price = 2.7M }

};

If we want to calculate total price off all fruits from the list we need to use Sum function and define a selector which is passed as a first argument.

var total = fruits.Sum(x => x.Price); // total = 14.0

1	var total = fruits.Sum(x => x.Price); // total = 14.0

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