Sum

In this chapter you will learn:

How to use Sum operator
Sum the total length of strings
Sum custom types

Get to know Sum operator

using System;//from jav a 2 s . com
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        decimal[] numbers = { 3, 4, 8 };
        decimal sumTotal = numbers.Sum(); // 15
        Console.WriteLine(sumTotal);

    }
}

The output:

Sum the total length of strings

The following returns the total length of each of the strings in the names array:

using System;/*ja  v  a 2 s  .c o  m*/
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        string[] names = { "Java", "C#", "Javascript", "SQL", 
              "Oracle", "Python", "C++", "C", "HTML", "CSS" };
        int combinedLength = names.Sum(s => s.Length);
        Console.WriteLine(combinedLength);

    }
}

The output:

Sum custom types

using System;//java  2  s .  co m
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class Employee {
    public int id;
    public string firstName;
    public string lastName;

    public static ArrayList GetEmployeesArrayList() {
        ArrayList al = new ArrayList();
        al.Add(new Employee { id = 1, firstName = "J", lastName = "R" });
        al.Add(new Employee { id = 2, firstName = "W", lastName = "G" });
        al.Add(new Employee { id = 3, firstName = "A", lastName = "H" });
        al.Add(new Employee { id = 4, firstName = "D", lastName = "L" });
        al.Add(new Employee { id = 101, firstName = "K", lastName = "F" });
        return (al);
    }

    public static Employee[] GetEmployeesArray() {
        return ((Employee[])GetEmployeesArrayList().ToArray(typeof(Employee)));
    }
}
public class EmployeeOptionEntry {
    public int id;
    public long optionsCount;
    public DateTime dateAwarded;

    public static EmployeeOptionEntry[] GetEmployeeOptionEntries() {
        EmployeeOptionEntry[] empOptions = new EmployeeOptionEntry[] {
        new EmployeeOptionEntry { 
          id = 1, 
          optionsCount = 2, 
          dateAwarded = DateTime.Parse("1999/12/31") },
        new EmployeeOptionEntry { 
          id = 101, 
          optionsCount = 2, 
          dateAwarded = DateTime.Parse("1998/12/31") }
      };
        return (empOptions);
    }
}
public class MainClass {
    public static void Main() {
        IEnumerable<EmployeeOptionEntry> options = EmployeeOptionEntry.GetEmployeeOptionEntries();
        long optionsSum = options.Sum(o => o.optionsCount);
        Console.WriteLine("The sum of the employee options is: {0}", optionsSum);
    }
}

Next chapter...

What you will learn in the next chapter:

How to use Take operator