LINQ Basics

Count and Sum

LINQ has aggregate methods for counting and adding values.

aggregate An aggregate method combines a sequence into one result.

Count and Sum

passing
CountSum.cs
Replay: real traced execution (multi-file project)
using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int passing = 70;
        int[] scores = { 55, 72, 90 };
        int passed = scores.Count(score => score >= passing);
        int total = scores.Sum();

        Console.WriteLine($"passing={passing}");
        Console.WriteLine($"passed={passed}");
        Console.WriteLine($"total={total}");
    }
}

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int passing = 60;
        int[] scores = { 55, 72, 90 };
        int passed = scores.Count(score => score >= passing);
        int total = scores.Sum();

        Console.WriteLine($"passing={passing}");
        Console.WriteLine($"passed={passed}");
        Console.WriteLine($"total={total}");
    }
}

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int passing = 85;
        int[] scores = { 55, 72, 90 };
        int passed = scores.Count(score => score >= passing);
        int total = scores.Sum();

        Console.WriteLine($"passing={passing}");
        Console.WriteLine($"passed={passed}");
        Console.WriteLine($"total={total}");
    }
}

  1. passing ← 70, passed ← 2, total ← 217

    5{6    static void Main()7    {8        int passing→ 70 = 70; //@passing=60, 859        int[] scores = { 55, 72, 90 };10        int passed→ 2 = scores.Count(score => score >= passing);11        int total→ 217 = scores.Sum();1213        Console.WriteLine($"passing={passing70}");14        Console.WriteLine($"passed={passed2}");15        Console.WriteLine($"total={total217}");16    }
    outputpassing=70
passed=2
total=217

  1. passing ← 60, passed ← 2, total ← 217

    5{6    static void Main()7    {8        int passing→ 60 = 60;9        int[] scores = { 55, 72, 90 };10        int passed→ 2 = scores.Count(score => score >= passing);11        int total→ 217 = scores.Sum();1213        Console.WriteLine($"passing={passing60}");14        Console.WriteLine($"passed={passed2}");15        Console.WriteLine($"total={total217}");16    }
    outputpassing=60
passed=2
total=217

  1. passing ← 85, passed ← 1, total ← 217

    5{6    static void Main()7    {8        int passing→ 85 = 85;9        int[] scores = { 55, 72, 90 };10        int passed→ 1 = scores.Count(score => score >= passing);11        int total→ 217 = scores.Sum();1213        Console.WriteLine($"passing={passing85}");14        Console.WriteLine($"passed={passed1}");15        Console.WriteLine($"total={total217}");16    }
    outputpassing=85
passed=1
total=217