Question about an exercise C# Basics course

C#
1

For the second exercise of the Array and Lists bit. I didn’t understand the entire code after looking at the solution.

The exercise:
2- Write a program and ask the user to enter their name. Use an array to reverse the name and then store the result in a new string. Display the reversed name on the console.

This being the solution:
public void Exercise2()
{
Console.Write("What’s your name? ");
var name = Console.ReadLine();

        var array = new char[name.Length];
        for (var i = name.Length; i > 0; i--)
            **array[name.Length - i] = name[i - 1];**

        var reversed = new string(array);
        Console.WriteLine("Reversed name: " + reversed);

I understand most of the code, aside from the bit marked. Can anyone explain what this does exactly?

2

Hi
Basically it is just copying separate letters from name in the reversed order into your array.

Example for the word testing

var array = new char[name.Length];

is equivalent to

var array = new char[7];

So you’re basically creating an array of char with 7 elements

for (var i = name.Length; i > 0; i--)
   array[name.Length - i] = name[i - 1];

7 times exclusively, you scan the name from its end backwards

and store the result in the array

image

This is important to understand the expressions that were used to :

  • stay within correct zero based indexes in both array and name.

  • Have them progress in opposite order.

Other ways you could have done that :

  • Using the hat operator (^) array[^i] = name[i - 1]; More @MSDN → System.Index
  • Using available static methods from Array type.
    static void ReverseName()
    {
        var name = "testing";

        var array = name.ToCharArray();
        Array.Reverse(array);
        var reversed = new string(array);
        Console.WriteLine("Reversed name: " + reversed);
    }
  • Using LINQ (certainly one of the big pleasures you’ll be introduced to later)
    static void ReverseName()
    {
        var name = "testing";

        var reversed = new string(name.Reverse().ToArray());
        Console.WriteLine("Reversed name: " + reversed);
    }

Hope this helps.

Cheers

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3

This was helpful thank you for your time and explanation! :blush:

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