C# Practice Exercises

Group Students with LINQ

GroupBy turns a sequence into keyed groups that can be aggregated independently.

How it works

Group records and calculate category averages.

Each grouping exposes its Key and can be queried with the normal LINQ aggregate operators.

Runnable C# example

Program.cs

using System;
using System.Linq;
record Student(string Name, string Grade, int Score);
class Program
{
    static void Main()
    {
        var students = new[] { new Student("Ada", "A", 95), new Student("Lin", "B", 84), new Student("Grace", "A", 91) };
        foreach (var group in students.GroupBy(s => s.Grade).OrderBy(g => g.Key))
            Console.WriteLine($"{group.Key}: {group.Average(s => s.Score):F1}");
    }
}

Expected output

A: 93.0
B: 84.0

Practice with the debugger

Set a breakpoint on an important assignment or condition, click Debug, and inspect the local values before stepping to the next line.