Summary - Array methods

C# course · Beginner · Lesson 64/116

Combine Sort, Reverse and Find to write a class list app.

Summary - Array methods

In this section you learned Array.Sort, Array.Reverse, Array.IndexOf, Array.Copy and Array.Find / FindAll. They all work in place or return new arrays; none removes the need to write loops, but each shortens the code.

Now we will combine them into a small class list app. Sorting, searching and finding the top score will come together in a single Main method.

Exercise Sort and print the top score

Sort the given int[] scores = { 78, 92, 65, 88 }; array with Array.Sort(scores). Then print the top score, that is scores[scores.Length - 1], with Console.WriteLine.

Show example solution

Sort with Array.Sort(scores);, then print the top score with Console.WriteLine(scores[scores.Length - 1]);.
Example solution:
using System;

class Program
{
    static void Main()
    {
        int[] scores = { 78, 92, 65, 88 };
        // Sort and print the top score
        Array.Sort(scores);
        Console.WriteLine(scores[scores.Length - 1]);
    }
}

Exercise Find a specific score

On the given int[] scores = { 78, 92, 65, 88 }; array, find the index of the value 65 with Array.IndexOf(scores, 65) and print it with Console.WriteLine.

Show example solution

Find the index with int idx = Array.IndexOf(scores, 65);, then print with Console.WriteLine(idx);.
Example solution:
using System;

class Program
{
    static void Main()
    {
        int[] scores = { 78, 92, 65, 88 };
        // Find the index of 65 and print it
        int idx = Array.IndexOf(scores, 65);
        Console.WriteLine(idx);
    }
}

Test yourself

What is the last element after sorting?
```
int[] scores = { 78, 92, 65, 88 };
Array.Sort(scores);
Console.WriteLine(scores[scores.Length - 1]);
```
- 78
- 92
- 65
- 88
Show answer

92 — Correct. The last element of an ascending sorted array is the largest: 92.

Search with IndexOf

int[] scores = { 65, 78, 88, 92 };
int idx = ____;
Console.WriteLine(idx);

Show answer

int[] scores = { 65, 78, 88, 92 };
int idx = Array.IndexOf(scores, 88);
Console.WriteLine(idx);

Match the concepts

Array.Sort

Sorts ascending
Array.Reverse

Reverses
Array.IndexOf

Finds index
Array.Find

First match

Summary - Array methods